Follow the latest on the explosions which have killed at least 34 people at Brussels' international airport and a metro station. Belgium's terror alert has now been raised to its highest level.
All updates in Universal Coordinated Time (UTC)
At least 34 have died from explosions which rocked the departure hall of Brussels' airport during rush hour on Tuesday morning. Another explosion hit the city's Maelbeek metro station near European Commission buildings, leading the institution to shut down operations for safety concerns.
18:28: Belgium's King Philippe has delivered an address to the nation. "Today our country is in grief. For each of us, March 22 will never again be a normal day," the monarch said. "We express all our support to members of the security forces, and we praise all those who spontaneously offered to help."
"Faced with this threat, we will continue to respond collectively, with determination, calm and dignity," the king added.
18:22: New York City's World Trade Center on Tuesday will be lit up in black, yellow and red in a show of solidarity with Belgium. Both Berlin's Brandenburg Gate and the Eiffel Tower in Paris have adopted the Belgian tricolore for the evening.
18:17: Belgian police have found an IS flag and another bomb during a raid in Brussels: media reports.
17:43: Belgian Prime Minister Charles Michel said during a press conference that the country would ramp up border controls, while also declaring three days of national mourning.
17:23: IS has released a statement claiming responsibility for the attacks. The terror organization said it targeted Belgium for its participation "in the international coalition against the Islamic State."
17:04: Belgian police appeal to public for help in finding terrorist suspect wanted in connection with airport attack.
16:49: Italian PM Matteo Renzi has reiterated the need for a streamlined and united defense strategy in Europe.
"The European Union needs to invest in a single defense and security structure. Europe has been discussing and arguing since 1954 about a common defense policy," Renzi said.
16:33: Britain's foreign ministry has advised Britons of all but essential travel to Brussels.
16:26: German Chancellor Angela Merkel has commented on today's attacks.
"We feel very close to our friends in Belgium today. Our disgust is just as boundless as the determination to defeat terrorism," Merkel said.
"My thoughts are also with those people now battling the consequences of these explosions in the hospital," she added.
16:17: Belgian security personnel have found and deactivated a third bomb at the airport.
16:01: Brussels' airport will remain closed at least through Wednesday, the airport's CEO announced, affecting some 24,000 passengers.
15:49: EU leaders, including the 28 heads of state and government, have released a joint statement condemning the Brussels attacks. "We will be united and firm in the fight against hatred, violent extremism and terrorism," the statement read.
15:48: US Democratic presidential candidate Bernie Sanders has released a statement in response to Wednesday's events.
"Today's attack is a brutal reminder that the international community must come together to destroy ISIS. This type of barbarism cannot be allowed to continue," the statement read, referring to alternate name for IS.
15:39: Belgium authorities have released surveillance footage of three suspects in connection with the airport attack. Two of the men are suspected of having been suicide bombers, while the third is supposedly still on the loose.
15:32: The so-called "Islamic State" (IS) terror organization has claimed responsibility for the attacks.
15:16: Security officials believe at least one of the explosions at Brussels international airport was due to a suitcase bomb, according to a US official who spoke on condition of anonymity.
The official also said that the explosives used in the attacks appear to be sophisticated. Investigators will examine them to determine whether or not they have the same characteristics as the explosives used in the Paris attacks last year.
15:05: The Eiffel Tower in Paris and Brandenburg Gate in Berlin will be illuminated with Belgium's colors tonight as a show of solidarity for Tuesday's attacks, reported DW's Doris Pundy in Brussels.
Other nations around Europe already paid tribute to the tragedy on Tuesday by having a moment of silence. The French National Assembly as well as Czech parliament and lawmakers in Spain held a minute of silence for the victims.
Paris Mayor Anne Hidalgo and Belgium's ambassador have also planned a silent gathering for Tuesday night.
At 10 Downing Street in London, the British Prime Minister's office raised the Belgian flag as a show of support.
14:34: There is a bomb alert at the Saint Pierre hospital, reported DW's Doris Pundy from Brussels.
Over 106 people have been injured due to the Maelbeek metro explosion, said Pundy, with many of the injuries including broken bones, cuts from flying glass, as well as nails which may have been in the bombs.
14:29: US President Barack Obama said the US will do "whatever is necessary to support our friend and ally Belgium," in the wake of terrorist attacks in Brussels.
"We must unite, we must be together regardless of nationality or race or faith in standing against the scourge of terrorism," Obama says in remarks during his visit to Cuba.
US Democratic presidential candidate Hillary Clinton said acts of terror "will not succeed."
"Today's attacks will only strengthen our resolve to stand together as allies and defeat terrorism and radical jihadism around the world," the former U.S. secretary of state said in a statement.
14:26: Quickly following the attacks in Brussels, thousands of social media users shared images of the country's most famous comic icon, Herge's Tintin, crying.
One cartoon, drawn by French film-maker and graphic novelist Joann Sfar, shows Tintin consoling his sidekick Captain Haddock: "Sometimes I want to leave for the Moon, Captain."
Others also shared cartoons of Brussels' famous "Manneken Pis" - or peeing boy - sculpture as a sign of solidarity following the attacks.
14:05: Railway stations in Brussels are set to reopen at 15:00 GMT with a heightened security presence, police said. The central station will remain closed for now, but 500 soldiers will be present at the southern and northern Brussels stations, reported La Libre newspaper.
13:57: German Foreign Minister Frank-Walter Steinmeier condemned the "murderous attacks" in Brussels, saying Europe stands in solidarity with Belgium.
German Interior Minister Thomas de Maiziere said it is still unclear whether or not German nationals were among those injured by the attacks. De Maiziere also said the terrorists attacked not only Belgium, but also "our freedom of mobility and everyone who is a part of the EU."
13:53: The US Embassy in Brussels has recommended that Americans in Belgium stay where they are and avoid public transportation.
"The US Embassy recommends sheltering in place and avoiding all public transportation," the statement said.
13:47: Belgium's Electrabel said the Tihange nuclear power plant on the border with Germany was not evacuated, although unnecessary staff "can leave."
13:37: A "suspect vehicle" has been blown up by the Belgian army's explosives team in the southern Brussels neighborhood of Ixelles, reported the area's police on Twitter. The operation took place near one of the university campuses of Vrije Universiteit Brussel.
Another university, the Universite Libre de Bruxelles, evacuated all of its campuses in Brussels and in the southern city of Charleroi following the attacks.
13:24: Brussels mayor Yvan Mayeur said at least 20 people died in the metro attack at Maelbeek near the EU headquarters.
"According to initial figures, there are around 20 dead with another 106 wounded, 17 of them gravely and another 23 seriously," Mayeur said, describing the scene at Maalbeek station as "very chaotic."
13:22: Police in London are asking Britons to send in pictures and video from those who may have witnessed the attacks in Belgium. The Metropolitan Police say they have "activated an online platform where images and videos can be uploaded which could provide important information for the investigating authorities."
13:17: A discarded bomb belt has been found at Brussels airport by Belgian police, reported Belgian private broadcaster VTM. A bomb squad is set to safely detonate the explosives.
13:14: A nuclear plant in Belgium near the border with Germany has been evacuated following the terrorist attacks in Brussels, reported Belga news agency, quoting local police.
13:08: Passengers are no longer being evacuated from the airport, though it is unclear whether the premises have been cleared or police are still securing the area, reports DW's Max Hofmann from Brussels.
12:52: Hezbollah, a Lebanese militant group, responded to the attacks in Brussels, saying Europe was being burnt by "fire" from the Middle East.
"The fire that Europe in particular and the world in general is being burnt by is the same one that some regimes ignited in Syria and other states in the region," Hezbollah said in a statement.
12:47: Social media users in Belgium are offering a safe place for those stranded on the streets using the hashtags #ikwilhelpen #openhouse #porteouverte, reported DW's Doris Pundy in Brussels.
12:37: The FBI has begun coordinating with their Belgian counterparts following the attacks in Brussels, said US officials on Tuesday.
US Defense Secretary Ash Carter and General Joseph Dunford, the chairman of the Joint Chiefs of Staff, were briefed on the explosions.
12:34: The death toll in the Brussels attacks has risen to 34, reported Belgian public broadcaster VRT. They say 20 people were killed in the Maelbeek metro train blast and 14 died due to explosions at the airport.
Belgian officials say that at least 136 have been injured in the attacks.
12:24: One person has been arrested on an outbound train from Brussels as it entered Amsterdam's Schipol airport, said DW's Doris Pundy in Brussels.
She added that despite prior reports the Brussels airport explosions targeted passengers at American Airlines check-in couters, the airline has now denied these claims.
"At this time there are no reported injuries to our employees. American Airlines check-in operates at row eight of the departure hall, and the explosions did not occur at row eight," the airline said in a statement.
"American Airlines is taking care of our employees and customers in Brussels after this morning's events," it added.
12:14: German airline Lufthansa canceled 25 flights in and out of Brussels following the attacks. On the airline's website, some 2,000 passengers will be affected by the cancellations.
Over 200 flights to Brussels were diverted or cancelled according to flight tracking services.
12:11: A third bomb and kalashnikovs have been found at Brussels airport where the evacuation is still ongoing, said DW's Doris Pundy. A thousand people have already been evacuated from the airport and are being held at a gymnasium in Zaventem.
Pundy also reports that raids have begun in Brussels and a crisis center has been set up for relatives of Tuesday's attack victims at Rue des Champs 71 in Etterbeek.
11:57: French President Francois Hollande said the blasts in Brussels struck at "the whole of Europe".
"Through the attacks in Brussels, the whole of Europe has been hit," Hollande said in a statement, urging the continent to take "vital steps in the face of the seriousness of the threat."
French Prime Minister Manuel Valls said: "We are at war. Over the past few months in Europe we have endured several acts of war."
US President Barack Obama has also been briefed on the attacks in Brussels during his visit to Cuba, a White House offical said.
"The president was apprised this morning of the explosions in Brussels, Belgium," the official said after the explosions hit Brussels airport and a metro station. "U.S. officials have been and will continue to be in close contact with their Belgian counterparts.
Russia's President Vladimir Putin said the explosions "show once more that terrorism knows no borders and threatens people all over the world", according to a Kremlin statement.
"The fight against this evil requires vital international cooperation," he added.
11:52: Social media users in Brussels have been documenting the shock and chaos following three explosions which rocked the Belgian capital leaving "scores" dead and wounded.
Some of the injured from the Maelbeek metro explosion were being cared for in a hotel lobby.
Twitter user Evan Lamos, one of those evacuated from the metro line, said his train was stopped between the Schuman and Maelbeek stations and that he could "hear a soft thudding in the distance."
He also shared the following video of passengers walking on the tracks as they were evacuated from the train:
Despite the panic, some social media users shared stories of helping strangers during metro evacuations.
11:43: A Slovenian diplomat was among those injured in the Brussels attacks, according to Solvenian Foreign Minister Karl Erjavec. In a press conference, he added that the diplomat was being treated in a hospital and did not have life-threatening injuries.
Media reports said the the diplomat was among those injured in the metro station blasts.
11:40: German President Joachim Gauck, who is on a state visit to China, spoke of his distress at hearing the news.
"The news of the cruel terror attacks at Brussels airport and the Brussels metro have shaken me deeply," said Gauck, who visited Belgium two weeks previously. "I condemn these terrible crimes, which have claimed so many victims, in the strongest possible terms. In the face of these acts of terrorist violence, Germany stands side by side with Belgium."
Peter Altmaier, German Chancellor Angela Merkel's chief of staff, called for solidarity with Belgium following the attacks, saying that "The terrorists will never win!"
11:27: The evacuation of the Maelbeek metro station has been completed, reported DW's Doris Pundy in Brussels. Eye witnesses say that there were two explosions in quick succession after a metro train departed.
Police in Brussels who had the day off are voluntarily coming in to work and the flags outside of Berlaymont - home to the European Commission - are flying at half-mast, reported Pundy.
11:20: Belgium's Health Minister Maggie De Block said the attack on Brussels' airport has so far left 11 dead and a total of 81 injured. Of those wounded, 31 have been very severely injured. They have been taken to 15 hospitals.
11:04: Belgian federal prosecutor Frederic Van Leeuw called all three explosions in Brussels "terrorist attacks." He also confirmed that "one attack was probably done by a suicide bomber."
11:02: German authorities have also significantly increased security measures at airports, train stations and the borders with Belgium, France, the Netherlands and Luxembourg following the Brussels explosions, said a federal police spokesman.
10:58: DW's Max Hoffman says people at the Brussels airport are still being evacuated.
10:56: Belgian authorities said they have increased security measures at nuclear power sites. Investigators in February discovered video footage of a senior Belgian nuclear official at the property of a key suspect in the Paris attacks.
10:47: Belgian Prime Minister Charles Michel says "what we feared has happened, we were hit by blind attacks," at a press conference. "This is a dark moment for our nation. We need calm and solidarity," he added.
Belgium's prosecutor said he could not give a concrete figure at this time for the number of dead or wounded, but said that several are seriously injured in the hospitals.
10:43: 15 people have now been reported killed after the Brussels Metro blast, reported public broadcaster RTBF quoting transport operator STIB.
They also said 55 people were wounded and 10 are in critical condition.
10:39: Police carried out a controlled explosion at Rue de la Loi following an evacuation of the area, reported Belgian public broadcaster RTBF.
10:32: Belgium deployed an additional 225 soldiers to the nation's capital.
10:22: French Interior Minister Bernard Cazeneuve said France will deploy an additional 1,600 police officers at the country's borders. Cazeneuve also called for the establishment of an EU task force to crack down on illegal documents, including fake passport and ID cards.
10:17: 23 people in total have died following "enormous" blasts in both the Brussels airport and metro system, reported firefighters to news agency AFP.
13 of the deaths occured due to the airport explosions while "around 10 killed at the Maalbeek metro station where there was an enormous explosion," Pierre Meys, spokesman for the Brussels fire brigade, told AFP.
10:05: Intelligence consultancy Lowlands Solutions' CEO Tomas Olivier told DW that the attacks across Brussels may have been launched by a "terrorist cell" preempting an intervention by Belgian counterterrorism authorities.
"We are witnessing a sophisticated, well-organized and planned terrorist attack in which a cell possibly related to Najim Laachraoui, associated to [Salah] Abdeslam, might have been responsible. Their modus operandi of multiple inbound suicide commandos in combination with a geographical spread took away the flexibility in response of the Belgian authorities," Olivier said.
"This attack was most likely initiated due to the fact that the terrorist cell needed to grasp the moment because of possible intervention of Belgian counterterrorism measures and activities in the last seven days," Olivier added.
09:55: The royal prosecutor in Brussels confirmed that the Zaventem airport blasts were a suicide attack, reports DW's Brussels correspondent Doris Pundy. The road to DW's Brussels studio has been blocked by security forces, she added.
09:42: Several political leaders have expressed concern over the events unfolding in Brussels.
Germany's Justice Minister said, "Today is a black day for Europe."
German Environment Minister Barbara Hendricks responds to the news from Brussels. "My thoughts are with the victims, their relatives, and friends." Germany's Anti-Discrimination agency called the explosions "horrific."
Belgium's national football team also tweeted their condolences for those killed and injured in the blasts.
The Bulgarian President Rosen Plevneliev said he "strongly condemns" the attacks. Iraq's Kurdistan Regional Government Foreign Minister Falah Mustafa said his "thoughts are with the families and friends of the victims."
09:27: Security at airports around Europe has been raised in light of the blasts in Brussels. Airports in Frankfurt, Paris, Amsterdam, as well as London's Gatwick airport, has stepped up security.
Some of the flights intended for Brussels have been diverted to Frankfurt airport.
09:25: Belgium's crisis center advised people to stay inside as all public transportation in Brussels has been closed.
09:12: 13 people have died as a result of the deadly explosions at Brussels' international airport and metro stations, according to local media in Brussels. Federal prosecutors said that 35 have been injured so far.
09:07: UK Prime Minister David Cameron announced he will be holding a COBRA meeting in response to the events in Brussels.
09:06: The European Commission has locked down its staff in response to explosions at the Brussels airport and possibly two metro stations which are located close to EU institutions.
09:05: A suicide bomber is responsible for the Brussels airport explosions which have killed at least 10 people so far, reported Belgian broadcaster VRT.
08:33: Brussels Transport Authority has closed all metro stations in Brussels following an explosion at the Maalbeek metro station which is situated close to the European Union headquarters. Police shut down several blocks surrounding the station and have continued widening the cordoned-off zone.
"The metro was leaving Maelbeek station when there was a really loud explosion. It was panic everywhere. There were a lot of people in the metro," Alexandre Brans, 32, told the Associated Press.
Passengers stuck on metro trains were evacuated following metro station closures.
08:29: At least 10 people were killed and over 30 injured in the bomb blast at the airport, reported public broadcaster RTBF citing the Saint-Luc hospital in Brussels.
08:24: Authorities in Belgium have raised the country's alert to its highest level, which indicates a "serious and imminent" threat, reported local media.
08:22: Another explosion has been confirmed at the Maalbeek metro station close to EU buildings, reported DW's Max Hoffmann.
08:00: Brussels airport has been closed until further notice, with no flights leaving or arriving at the airport.
07:40: Smoke could be seen rising from the terminal building where the windows had been shattered. A video shared by Twitter user Anna Ahronheim, who did not take the video herself, shows people running away from the building amidst
07:30: At least one person has died as a result, federal police told news agency Belga. Witnesses on the scene said that several people were injured.
"There were two blasts in the departure hall. First aid team are in place for help," said airport spokeswoman Anke Franse.
Compiled by various DW staff over the course of the day (with AP, AFP, dpa, Reuters)