More Coordinated Blasts Shake London

A string of blasts on the London subway system and a bus sent screaming passengers fleeing in panic and wounded at least one person Thursday, exactly two weeks after the deadliest terror attack on Britain.

"We know that we had four explosions or attempted explosions simultaneously," London police chief Ian Blair told reporters. "At the moment the casualties appear to be very low in the explosions. The bombs appear to be smaller than on the last occasion. We don't know the implications for this yet -- clearly this is a very serious incident."

Dozens of police and fire engines scrambled to the scenes, evacuating three subway stations and cordoning off a wide area in eastern London around a double-decker bus in which the upper-floor windows were blown out.

Police said they had sent armed officers to investigate an "incident" at University College Hospital in central London. A spokesman was unable to confirm reports on Sky News about a man with a device with protruding wires attached to him seen in the area of the hospital. Police said the incident had been contained without providing further details.

A city already traumatized

Stations at Oval in southern London, Warren Street to the north and Shepherd's Bush to the west were evacuated. Police said initial investigations of Warren Street and Oval stations found no sign of chemical agents.

Four subway lines were temporarily shut down.

The blasts hit a city traumatized by the July 7 attacks, in which 56 people were killed including four suspected al-Qaeda suicide bombers who blew up three subway trains and a double-decker bus.

Chaos, panic, witnesses say

Back on the streets, passengers who had fled the trains reported panic and chaos below ground.

Victoria Line passenger Ivan McCracken said he heard a traveler's backpack had exploded on the subway outside Warren Street station.

"I was in a middle carriage and the train was not far short of Warren Street station when suddenly the door between my carriage and the next one burst open and dozens of people started rushing through, some were falling and there was mass panic," he told Sky News.

"It was difficult to get the story from any of them what had happened but when I got to ground level there was an Italian young man comforting an Italian girl who told me he had seen what had happened. He said that a man was carrying a rucksack and the rucksack suddenly exploded. It was a minor explosion but enough to blow open the rucksack. The man then made an exclamation as if something had gone wrong. At that point everyone rushed from the carriage."

"I could just smell smoke"

Another witness, Abena Adofo, 23, told AFP that people were running into her carriage. "I could just smell smoke and I saw lots of people panicking," she said. "I was just trying to be calm and get out. The smell of smoke was coming from the end of the carriage."

Stagecoach, which owns the number 26 bus involved in the incident, said the driver heard a bang at around 12:30 p.m. London time.

The bus had left Waterloo and was in the Shoreditch neighborhood when the incident happened.

"The driver heard a bang which appeared to come from the upper deck," a spokesman told AFP. "When he went upstairs to investigate, the windows on the upper deck were blown out. The bus is structurally intact and we don't have any reports of injuries."

British Prime Minister Tony Blair urged the public to stay calm.

"We know why these things are done -- they are done to scare people," he told reporters. "Fortunately, in this instance, there appear to have been no casualties ... We've got to react calmly. To react in any other way is to engage in the game they want us to engage in."