http://en.wikipedia.org/wiki/7_July_2005_London_bombings

08:51: Initial reports of an incident between Liverpool Street and Aldgate East tube stations, either an explosion or a collision between trains. The reports from the two stations were initially thought to relate to two separate incidents.
08:56: Explosion on train between Kings' Cross and Russell Square. Eyewitnesses report explosion appeared to come from outside the train.
09:17: Explosion on train at Edgware Road station.
09:28: Tube operator Metronet says the incident was caused by some sort of power surge.
09:33: Reports of an incident at Edgware Road tube station. Reports that passengers on a train hit by an explosion attempted to break windows with umbrellas in order to escape.
09:46: British Transport Police announce there had been more explosions at Kings' Cross, Old Street, Moorgate, and Russell Square.
09:47: Explosion on bus at Upper Woburn Place/Tavistock Square. Fatalities, but number not yet known.
09:49: Whole London Underground system shut down.
10:00: National Grid announce there had been no problem with power surges.
10:40: First report of fatalities, government source speaks of 20 dead.
11:08: Bus services suspended across central London.
11:10: Metropolitan Police Commissioner Sir Ian Blair confirms fears that it is a co-ordinated terror attack, but appeals for calm, asking people not to travel to London or make unnecessary calls to the emergency services.
12:00: Prime Minister Tony Blair speaks out on the incident, calling the attacks a coordinated series of "barbaric" terrorist attacks.