Five blasts rocked the London subway and one tore open a packed double-decker bus during the morning rush hour Thursday, sending bloodied victims fleeing in what a shaken Prime Minister Tony Blair called "barbaric" terrorist attacks.
A US law enforcement official said at least 40 people were killed and London hospitals reported more than 300 injured.
The US official spoke on condition of anonymity because British officials have yet to make public the death toll. US authorities learned of the number from their British counterparts, according to the official.
Traffic camera image from video of the Russell Square area of central London following an explosion on board a bus on July 7, 2005. What is believed to be the roof of the double-decker bus can be seen centre right.
Text: Jane Wardell, Associated Press
AP Photograph: London Transport via APTN