Four blasts rocked the London subway and tore open a packed double-decker bus during this morning's rush hour, sending bloodied victims fleeing after what a shaken Prime Minister Tony Blair called a string of "barbaric" terrorist attacks. Here is a timeline of the events in London.
London blasts: At a glance
All times are in British Summer Time, which is five hours ahead of Eastern Standard Time.
08:50 a.m. Three blasts occur in the London subway within 50 seconds of one another
09:15 a.m.: Press Association reports emergency services called to Liverpool Street Station after reports of an explosion
09:24 a.m.: Transport Police say the incident was possibly caused by a collision between two trains, a power cut or a power cable exploding. Police report "walking wounded"
09:33 a.m.: Passengers are told that all London Underground services are being suspended because of a power fault across the network
09:33 a.m.: London Underground reports "another incident at Edgware Road" station
09:40 a.m.: Transport Police say power surge incidents have occurred on the Underground at Aldgate, Edgware Road, King's Cross, Old Street and Russell Square stations
10:02 a.m.: Scotland Yard says it is dealing with a "major incident"
10:09 a.m.: Witness Christina Lawrence, who was on a train leaving King's Cross, tells BBC News 24: "There was a loud bang in the tunnel and the train just stopped and all of a sudden it was filled with black, gassy smoke and we couldn't breathe"
10:14 a.m.: An eyewitness tells PA that a bus has been ripped apart in an explosion in central London
10:21 a.m.: Scotland Yard reports "multiple explosions" in London
10:23 a.m.: Transport Police confirm an explosion on a bus in Tavistock Square
10:25 a.m.: A BBC reporter traveling with British Prime Minister Tony Blair to the G8 summit in Scotland says 10 Downing Street is "still unsure" whether the explosions are a terrorist attack
10:25 a.m.: PA reports two buses damaged in explosions - one in Russell Square and another in Tavistock Square. Witness Belinda Seabrook said of the Russell Square blast: "I was on the bus in front and heard an incredible bang, I turned round and half the double decker bus was in the air"
10:25 a.m.: Transport union officials say they have reports of explosions on three buses, Associated Press reports
10:39 a.m.: All London hospitals have been put on major incident alert, a hospital spokesman tells PA
10:49 a.m.: Police say there are serious casualties, but no deaths are confirmed, PA reports
10:51 a.m.: A passenger on a train at Edgware Road says he saw several bodies in the wreckage. A police spokesman says two trains remain stuck in tunnels at Edgware Road
10:53 a.m.: British Home Secretary Charles Clarke makes a statement outside Downing Street about "dreadful incidents" causing "terrible injuries." He says Blair has been informed and advises the public in London not to make unnecessary journeys
10:55 a.m.: A doctor tells Reuters there are at least 90 casualties at Aldgate station
11:18 a.m.: London Metropolitan Police Commissioner Sir Ian Blair tells the BBC he knows of "about six explosions," one on a bus and the others related to Underground stations. He says he believes the six affected areas are Edgware Road, King's Cross, Liverpool Street, Russell Square, Aldgate East and Moorgate, but says it is "still a confusing situation." He advises Londoners to "stay where you are -- all of London's transport is currently disabled" -- he refuses to confirm any fatalities
11:25 a.m.: "We have at least two fatalities, but still unconfirmed," a police spokesman tells the AFP news agency
11:26 a.m.: The president of the European Parliament, Josep Borrell, blames terrorism for a "co-ordinated series of attacks" and "confirmed deaths"
11:30 a.m.: Signs on major roads into London warn: "Avoid London. Area closed. Turn on radio"
12:05 p.m.: The Bishop of London, Richard Chartres, said: "This is a grave day for London. Our thoughts and prayers are with the injured and bereaved"
12:05 p.m.: Blair, at the G8 summit, says there has been "a series of terrorist attacks in London … people have died and are seriously injured … It is reasonably clear this is designed and timed to coincide with the opening of the G8." He says he will return to London within hours, but that the summit will continue without him
12:10 p.m.: The BBC reports it has located a Web site linked to al Qaeda with a 200-word statement saying it carried out the bombings
12:15 p.m.: The ambulance service says there are people still trapped at King's Cross station, and efforts are being made to rescue them
12:46 p.m.: Pope Benedict XVI condemns the "inhuman" attacks
12:55 p.m.: Clarke tells the House of Commons that four explosions had been confirmed, three on trains and four on a bus. "We do not know who or what organisations are responsible for these terrible criminal acts," he says. He says the Underground will remain closed all day.
1:07 p.m.: G8 leaders issue a statement, read by Blair, saying: "We condemn utterly these barbaric attacks"
1:13 p.m.: The mayor of London, Ken Livingstone, condemns a "cowardly terrorist attack" and says Londoners responded "calmly and courageously"
1:25 p.m.: Blair leaves the G-8 summit by Chinook helicopter and heads back to London
1:33 p.m.: U.S. President George W Bush, speaking at the G-8 summit, condemns the attacks, saying that the blasts show the war on terror must continue
1:44 p.m.: The Archbishop of Canterbury, Dr. Rowan Williams, describes the attacks as appalling and calls on all religious leaders to stand and work together for the well-being of the nation
1:53 p.m.: Russian President Vladimir Putin expresses his condolences over the attacks and calls on all countries to unite in the fight against international terrorism
2:18 p.m.: A Transport for London spokeswoman says the bus hit by the explosion was a number 30, traveling from Hackney to Marble Arch
3:10 p.m.: Blair returns to London
3:25 p.m.: At a joint emergency services press conference, officials say 33 deaths have been confirmed and 45 people have been seriously or critically wounded in four subway blasts and one bus explosion. Some 300 patients reportedly have minor injuries including shock and cuts
3:35 p.m.: Police Deputy Assistant Commissioner Brian Paddick at conference says it was too early to tell whether suicide bombers were responsible for the four blasts
3:46 p.m.: London police say there have been no arrests in connection with the blasts so far and that they're "keeping an open mind as to who the perpetrators might be"
3:55 p.m.: U.S. raises its terror alert level to orange for rail and subway systems, but not for airlines, officials say
4:03 p.m.: Scotland Yard issues a casualty hotline number for people worried about their relatives after this morning's bombings in London. The number is 0870 1566 344
British Broadcasting Corporation contributed to this report.