Following is a timeline detailing the sequence of events that took place as a series of multiple explosions rocked central London. All times are British Standard Time.

08:51 The first blast occurs between Aldgate East and Liverpool Street tube stations, about 91 metres into the tunnel from Liverpool Street station.

08:56 The second explosion occurs between Russell Square and King's Cross tube stations.

09:15 British Transport Police tell news agencies an explosion has struck London's financial district in the area near Liverpool railway station.

09:17 The third blast occurs on a train heading into Edgware Road station, blowing a hole through a wall onto another train in an adjoining platform.

09:24 British Transport Police say the Liverpool Street incident was possibly caused by a collision between two trains, a power cut or a power cable exploding.

09:27 Metronet, the subway maintenance company, says a power surge has caused an explosion in a subway station.

09:33London Underground reports another incident at Edgware Road station.

09:33 Passengers are told that all London Underground services are being suspended because of a power fault across the transportation network.

09:40 British Transport Police say power surge incidents have occurred on the network at Aldgate, Edgware Road, King's Cross, Old Street and Russell Square stations.

09:47 There is an explosion on a bus near Tavistock Square in central London. Eyewitnesses described the bus as being "ripped open like a can of sardines."

09:53 Metronet says the entire London subway network has been shut down, news agencies report.

10:02 Scotland Yard says it is dealing with a "major incident"

10:21 Scotland Yard reports "multiple explosions" in London.

10:23 British Transport Police confirm an explosion on a bus near Tavistock Square.

10:25 Transport union officials say they have reports of explosions on three buses.

10:39 All London hospitals are put on major incident alert, a hospital spokesman says.

10:49 Police say there are serious casualties, but no deaths are confirmed, Associated Press reports.

1053 Home Secretary Charles Clarke makes a statement outside Downing Street about "dreadful incidents" causing "terrible injuries."

11:07 All bus services suspended in London, news agencies report.

11:10 Police say they have reports of two deaths and nine injuries at Aldgate East subway station.

11:15 Police say there were at least six explosions in London.

11:18 London's Metropolitan Police Commissioner Sir Ian Blair advises Londoners to "stay where you are - all of London's transport is currently disabled."

11:26 European Parliament President Josep Borrell blames terrorism for a "co-ordinated series of attacks."

11:30 Signs on major roads into London caution: "Avoid London. Area closed. Turn on radio"

11:35: London police chief tells Reuters there are "indications of explosives" at one of the blast sites.

12:00: British Prime Minister Tony Blair says the "barbaric" London blasts are terrorist attacks and were designed to coincide with the G8 summit in Scotland. He will return to London but the summit will continue without him.

12:15 The ambulance service says there are people still trapped at King's Cross station, and efforts are being made to rescue them.

12:27 Police and hospital officials tell Reuters that a total of 185 people are wounded across London.

12:35 Scotland Yard revises the number of blasts down to four.

13:07 G-8 leaders issue a statement, read by Tony Blair, saying: "We condemn utterly these barbaric attacks"

13:13 The Mayor of London, Ken Livingstone, condemns a "cowardly terrorist attack" and says Londoners responded "calmly and courageously."

13:25 Blair leaves Gleneagles, Scotland on a helicopter to return to London.

15:30 Police confirm that at least 33 people have been killed. As many as 300 have been wounded, 45 of those with critical and serious injuries.