LONDON (AP) - Three blasts rocked the London subway and one tore open a packed double-decker bus during the morning rush hour Thursday, sending bloodied victims fleeing after what a shaken Prime Minister Tony Blair called "barbaric" terrorist attacks. A U.S. law enforcement official said at least 40 people were killed and London hospitals reported more than 300 wounded.
Blair said the "terrorist attacks" were clearly designed to coincide with the opening of the G-8 summit in Gleneagles, Scotland. They also came a day after London won the bid to host the 2012 Olympics.
The explosions hit three subway stations and a double-decker bus in rapid succession between 8:30 and 9:30 a.m. Implementing an emergency plan, authorities immediately shut down the subway and bus lines that log 8.4 million passenger trips every weekday. It brought the city's transportation system to a standstill and left many central London streets deserted.
"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."
Blair, flanked by fellow G-8 leaders, including President Bush, said: "We shall prevail and they shall not."
Earlier, a shaken Blair said, "Whatever they do, it is our determination that they will never succeed in destroying what we hold dear in this country and in other civilized nations throughout the world."
He then departed by helicopter back to London. He said the meeting of the world leaders would continue.
President Bush later warned Americans to be "extra vigilant" as they head to work after the deadly explosions in London. He said he had conferred with federal homeland security officials back in Washington.
A group calling itself "The Secret Organization of al-Qaida in Europe" posted a claim of responsibility for the blasts, saying they were in retaliation for Britain's involvement in Iraq and Afghanistan.
The statement, which also threatened attacks in Italy and Denmark, was published on a Web site popular with Islamic militants, according to Elaph, a secular Arabic-language news Web site, and Der Spiegel magazine in Berlin, which published the text on their Web sites.
European stocks dropped sharply after the blasts, with exchanges in London, Paris and Germany all down about 2 percent. Insurance and travel-related stocks were hit hard, and the British pound also fell. Gold, traditionally seen as a safe haven, rose.
The U.S. official spoke on condition of anonymity because British officials have yet to make public the death toll. U.S. authorities learned of the number from their British counterparts, according to the official.
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.
London Mayor Ken Livingstone said the blasts that ripped through his city were "mass murder" carried out by terrorists bent on "indiscriminate ... slaughter."
"This was not a terrorist attack against the mighty or the powerful ... it was aimed at ordinary working-class Londoners," said Livingstone, in Singapore where he supported London's Olympic bid. Giselle Davies, an International Olympic Committee spokeswoman, said the committee still had "full confidence" in London.
Jay Kumar, a business owner near the site of the blast that destroyed a double-decker bus at Russell Square in central London, said he ran out of his shop when he heard a loud explosion. He said the top deck of the bus had collapsed, sending people tumbling to the floor.
Many appeared badly injured, and bloodied people ran from the scene.
"A big blast, a big bomb," he told The Associated Press. "People were running this way panicked. They knew it was a bomb. Debris flying all over, mostly glass."
"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.
Traces of explosives were found at two explosion sites, a senior police official said. Britain's Home Secretary Charles Clarke said there were three explosions in the subway and one on a bus.
Police confirmed fatalities but had not confirmed any numbers by early afternoon.
Pope Benedict XVI deplored the "terrorist attacks," calling them "barbaric acts against humanity," and said he was praying for the families of the victims.
Sir Ian Blair, London's police chief, said he was concerned the explosions were a coordinated attack but said he wouldn't speculate on who was responsible. He said officials had found indications of explosives at one of the sites.
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, 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.
On March 11, 2004, terrorist bombs on four commuter trains in Madrid killed 191 people.
