MORE than 50 people were feared dead last night and an estimated 700 were injured as London became the front line in the war against terror.

Terrorists - believed to be Islamic militants - launched a devastating series of co-ordinated bomb attacks across the city.

There were three explosions on Underground trains and one blew apart a double-decker bus leaving people dead, dying and maimed.

Police said they had received no warning before the bombs went off during the rush hour.

Last night, as anti-terrorist detectives began a painstaking search of the scenes for clues, the death toll looked set to rise still further.

Scotland Yard officially confirmed that at least 37 people were killed and there were 700 casualties, including 45 seriously, 300 of whom were taken to hospital by ambulance.

Death and destruction rolled across central London in 60 terrifying minutes as world leaders sat down to business in Scotland at the G8 summit.

The first explosion occurred in a train 100 yards from Liverpool Street station at 8.51am. Seven people died.

As emergency services raced to the station, a second bomb went off between King's Cross and Russell Square killing 21 people.

At 9.17am, a bomb exploded on a train at Edgware Road Tube station killing five people.

The force of the blast punched through the tunnel and damaged two other trains waiting at platforms.

Then at 9.47am, a bomb was detonated on a double-decker bus in Tavistock Square tearing the roof off and sending shrapnel flying through the air.

Tragically, some of the commuters who left King's Cross station to catch buses after the Tube was closed following the explosion are thought to have become victims of the final bomb blast.

Scotland Yard said two people were confirmed dead in the bus blast but eyewitnesses spoke of more bodies.

Chris Pearson, a father-of-three from Blackwell, Darlington, travelled to King's Cross Station by train yesterday morning, and arrived shortly after the first blast.

He saw the double-decker bus, minutes after it had been blown apart.

"The street was cordoned off by that time, but you could see the whole roof had been blown off," he said.

"I took refuge in Russell Park, there were about 200 people. No one knew what was happening, but I didn't want to be near any buildings or any traffic. When police evacuated the park, I didn't know where to go.

"I walked about half a mile and went to a pub - that was when I found out what had happened."

Martin McTague, from Heighington, near Darlington, was in London on a business trip and was staying in a hotel near King's Cross.

"I went outside about ten minutes after the first bomb went off, it was just chaotic," he said.

"There seemed to be hundreds of people in the street all heading towards King's Cross, no one knew what was going on, I think they just knew they had to get away. The sound of sirens seems to be the enduring memory, they were just everywhere."

David Simister, Yorkshire Water public relations and campaigns manager, was in the capital yesterday morning. He said: "It was absolutely appalling - like a scene from the film The Day After Tomorrow.

"At the time, there was a lot of misinformation about power surges on the Underground, but we saw a man being helped out of Euston station covered in blood.

"We're just so grateful not to have been involved in any of the blasts.

"There hasn't been any panic, but it's fair to say that the atmosphere in London was very tense."

Ambulance crews, paramedics and doctors were forced to treat the worst injuries on the platforms of Underground stations. More than 100 ambulances were used to ferry the injured to hospital.

Tube stations throughout London were closed and all bus services suspended. People travelling to and from the capital found their trains cancelled. Last night, transport officials announced that all operations from King's Cross were expected to be back to normal by noon today.

GNER advised passengers to avoid travelling to London, but said it would be running half hourly services from Peterborough to Scotland today.

Fears the explosions could cause a financial meltdown proved unfounded. The FTSE 100 index of leading shares plunged more than 200 points at one point yesterday as traders reacted to the bombings.

At one point, the blue-chip index stood 207.5 points lower but later recovered some of its poise to limit the losses to 71 points.

Prime Minister Tony Blair learned of the devastation minutes after holding a joint news conference at the G8 summit with his partner in the war on terror President George Bush. After staging a show of unity with leaders present at the summit, he flew back to London to take charge of the crisis.

Last night, Mr Blair pledged that Britain would not be intimidated by the terrorists and promised intense police and security service action to bring the bombers to justice.

Foreign Secretary Jack Straw said last night that the London bombings had "the hallmarks of an al Qaida-related attack".

Mr Straw, speaking at Gleneagles where he was chairing a round of G8 summit talks in the absence of Mr Blair, said in a television interview: "There's an assumption obviously that this is an al Qaida-based organisation.

"It has the hallmarks of an al Qaida-based organisation and also its ruthlessness."

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