A series of deadly explosions rocked the London subway and tore open a packed double-decker bus during the morning rush hour Thursday in what a shaken Prime Minister
British officials confirmed two deaths, but a U.S. law enforcement official said at least 40 people were killed in the blasts. The U.S official spoke on condition of anonymity because British officials have yet to make public the death toll.
London hospitals reported more than 300 people were injured.
Blair said it was clear the attacks were designed to coincide with the opening of the G-8 summit in Gleneagles, Scotland. The prime minister left the summit to return to London, but said the deadly explosions would not halt the work of the annual meeting.
"We will not allow violence to change our societies or our values nor will we allow it to stop the work of this summit," Blair said in a statement on behalf of the Group of Eight leaders. "We will continue our deliberations in the interest of a better world," he said a day after London was awarded the 2012 Olympics.
President Bush offered his condolences to the British people after the blasts. "The war on terror goes on," Mr. Bush said. He warned Americans to be "extra vigilant" as they head to work.
Top U.S. counterterror officials said there were no plans to increase the current alert status. The Homeland Security Department said there are also no indications of an imminent attack on U.S. interests. A Homeland Security official told CBS News the government's "interagency incident management group" is meeting to "assure full situational awareness."
Britain's Home Secretary Charles Clarke said there were three explosions in the subway and one on a bus. A senior police official said traces of explosives were found at two explosion sites.
Police reported "a number of fatalities" at one London subway station. "Things are still relatively confused," Superintendent John Morgan told reporters.
Officials at seven major hospitals surveyed by The Associated Press reported that 334 people had been wounded, including more than 120 who were treated and released. Police said 150 had been seriously injured.
A group calling itself ``The Secret Organization of al Qaeda in Europe'' posted a claim of responsibility for the blasts, saying they were in retaliation for Britain's involvement in Iraq and Afghanistan. The Web statement, republished on the site of the German magazine Der Spiegel, could not be immediately confirmed.
"It was chaos," said Gary Lewis, 32, who was evacuated from a subway train at King's Cross station. "The one haunting image was someone whose face was totally black and pouring with blood."
"This was not a terrorist attack against the mighty or the powerful, it is not aimed at presidents or prime ministers, it was aimed at ordinary working-class Londoners," said Livingstone, in Singapore where he supported London's successful bid to host the 2012 Olympics. "We know what the objective is. They seek to divide London."
Denying an earlier report, Israeli Foreign Minister Silvan Shalom said that Israel was not warned by Scotland Yard in advance of the blasts.
This year's summit of the G-8 countries — the United States, Britain, Canada, France, Germany, Italy, Japan and Russia — was being held at an exclusive 850-acre golf resort in Scotland.
The leaders – already protected by extraordinary security measures that local authorities said were sufficient for now – planned to proceed with discussions on the issues of global warming and African poverty that Blair has made the centerpiece of the gathering.
"All of our countries have suffered from the impact of terrorism," the leaders said. "Those responsible have no respect for human life."
One witness, Darren Hall, said some passengers emerging from an evacuated subway station had soot and blood on their faces. He told BBC TV that he was evacuated along with others near the major King's Cross station and only afterward heard a blast.
Police confirmed an explosion destroyed a double-decker bus at Russell Square in central London. Dow Jones Newswires reported that police said there were explosions on two other buses.
"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," Belinda Seabrook told Press Association, the British news agency.
She said the bus was packed with people. "It was a massive explosion and there were papers and half a bus flying through the air," she said.
Police said incidents were reported at the Aldgate station near the Liverpool Street railway terminal, Edgware Road and King's Cross in north London, Old Street in the financial district and Russell Square in central London, near the British Museum.
Bradley Anderson, a subway passenger, told Sky News that "there was some kind of explosion or something" as his train reached the Edgware Road station in northeast London.
"Everything went black and we collided into some kind of oncoming train," Anderson said.
Simon Corvett, 26, who was on an eastbound train from Edgware Road station, said: "All of sudden there was this massive huge bang."
"It was absolutely deafening and all the windows shattered," he said. "There were just loads of people screaming and the carriages filled with smoke.
"You could see the carriage opposite was completely gutted," he said. "There were some people in real trouble."
London's cell phone network was working after the explosions but was overloaded and spotty, limiting communication.