"On 7 July 2005, beginning at 08:49, during the height of morning rush hour, a series of four bomb explosions struck London’s transport system. Three Underground trains were hit within half an hour, and a bus a further half an hour after that. At least 40 died. The number of injured treated is at least 700. At least one news report has quoted 360 injured . Fox News reported 700 injured. This number is expected to rise as authorities survey the impact of the blasts. It is the worst terrorist attack to take place within the United Kingdom since the 1988 bombing of Pan Am Flight 103, which killed upwards of 200 people.
Metropolitan Police Service Commissioner Sir Ian Blair has said that explosions were probably the result of a "major terrorist attack" but did not wish to speculate on the organisation involved. The bombings came while the UK hosted the first full day of the 31st G8 summit at Gleneagles Hotel, Scotland, and a day after London won the bid to host the 2012 Summer Olympic Games. The Formula 1 British Grand Prix is also scheduled for this weekend, but will still go ahead.
The incidents led to the immediate evacuation of many tube stations, as well as the complete shut-down of the London Underground network. Roads near the affected stations were closed, severely affecting road traffic. Mainline services into London stations Euston, Paddington, Liverpool Street and King’s Cross terminated outside the city for most of the day, though all but Kings Cross had fully re-opened by 17:30. The city’s bus network was shut down in the central zone (Zone 1) until approximately 16:00.
British Prime Minister Tony Blair has described the attacks as "barbaric." "Our determination to defend our values and our way of life is greater than their determination to cause death and destruction to innocent people in a desire to impose extremism upon the world," he said. Mayor Ken Livingstone, speaking from Singapore. where he was promoting the city’s Olympic bid, called it a "cowardly attack": "This was not a terrorist attack against the mighty and the powerful. It was not aimed at Presidents or Prime Ministers. It was aimed at ordinary, working-class Londoners, black and white, Muslim and Christian, Hindu and Jew, young and old. It was an indiscriminate attempt to slaughter." 
There’s a lot more at the Wikipedia, replete with links . . .