Violent clashes broke out between protesters and security forces in Kazakhstan's largest city, Almaty, on Thursday.
City police spokeswoman Saltanat Azirbek told a local news channel that "dozens of attackers were liquidated," when they tried to storm government buildings.
Authorities said at least 18 police officers died, including one who was found beheaded.
The mayor's office was also reportedly set on fire after demonstrators broke into the building.
The fatalities came a day after the army was called in to quell increasingly volatile unrest. Witnesses said they saw armored vehicles and dozens of troops moving on Almaty's main square. Gunfire was also reported.
DW's Emily Sherwin, speaking in Moscow, said, "There is still an emergency situation across the country. Banks are closed and there have been reports of shots fired and explosions being heard."
Police said they arrested about 2,000 in Almaty, according to the Russian news agency TASS. They are prepared to stay for days or weeks if need be, Russian state-run RIA reported.
EU calls for restraint as government caps fuel prices
As the European Commission appealed for "restraint" and a "peaceful resolution" in Kazakhstan, Moscow issued a statement declaring its support for a "counter-terrorist" operation there.
"We regard the recent events in a friendly country as an attempt, inspired from the outside, to undermine the security and integrity of the state by force, using trained and organized armed formations," said the Russian Foreign Ministry.
In a bid to stop the violence, the Kazakh government announced later on Thursday that it was putting a 180-day moratorium on the fuel price hikes that kicked off the protest, citing a need to "stabilize the socioeconomic situation."
Russia-led alliance sends troops
The Collective Security Treaty Organization (CSTO), a Moscow-based alliance of six former Soviet countries, has sent troops to Kazakhstan to quell the unrest. Moscow said CSTO forces would number 2,500.
President Kassym-Jomart Tokayev had appealed to CSTO for aid in clamping down on protests.
"Peacekeeping forces of the Collective Security Treaty Organization were sent to the Republic of Kazakhstan for a limited time to stabilize and normalize the situation," the CSTO secretariat said in a statement posted by Russian Foreign Ministry spokeswoman Maria Zakharova.
The deployment included units of the armed forces of Russia, Belarus, Armenia, Tajikistan and Kyrgyzstan, the statement added.
Later on Thursday, the Kazakh government was quoted by Russian news agencies as saying it was temporarily banning foreigners from entering the country.
The announcement came after German airline Lufthansa said it was no longer offering regular flights to Almaty after demonstrators took over the city's airport.
Middle East carriers FlyDubai and Air Arabia had also announced that they were suspending flights to Kazakhstan.
Kazakhstan's National Bank has temporarily suspended all financial institutions and the internet is largely down across the country as the unrest continued for a third consecutive day.
What sparked the Kazakh protests?
The demonstrations in Almaty and the Kazakh capital, Nur-Sultan, began in response to a new law that came into effect on January 1. The law ended price controls for fuel, sending the cost of liquefied petroleum gas skyrocketing. This gas is used to power many vehicles, as it has been kept cheaper than gasoline.
The government of Prime Minister Askar Mamin has resigned, and President Tokayev has declared a nationwide state of emergency and imposed a curfew.
Tokayev has called the demonstrators "terrorist gangs" who were "undermining of the integrity of the state."
es/fb (AP, dpa, Reuters)