On Thursday 7 July 2005, a series of four bomb explosions struck London's transport system during the morning rush hour. Three London Underground trains were hit almost simultaneously, and a London Bus was hit almost one hour later. 49 are confirmed dead, with 700 injured, of whom about 350 required treatment (22 of these being in a serious or critical condition). It is thought that the confirmed death toll will be nearer 70 or 80, as the recovery operation is still ongoing in the deep tunnels. About 30 people have been named as missing.
The incidents led to the complete shutdown of the London Underground network and the closure of many roads near the affected stations. Mainline train services into many London stations terminated outside the city for most of the day, and the city's bus network was shut down in the central zone (Zone 1).
The bombers have not yet been identified but Metropolitan Police Service Commissioner Sir Ian Blair has said that they were most likely part of a terrorist cell based in the UK, possibly affiliated to al-Qaeda. The bombings came while the UK hosted the first full day of the 31st G8 summit at Gleneagles Hotel in Perthshire, and a day after London was chosen to host the 2012 Summer Olympics.