London’s entire underground railway network was closed down on Thursday after a series of explosions that caused a large number of casualties and at least 33 deaths, police said.
An explosion ripped through a double-decker bus in the centre of London just minutes after blasts rocked the underground, police said.
Authorities have suspended all bus services in London.
Sky News showed a picture of a mangled red bus and said it appeared London had come under a terror attack.
At least six explosions rocked the city, police officials said.
British Home Secretary Charles Clarke said there had been ”terrible injuries” in the multiple attacks on the transport system.
The minister was speaking as the Cabinet met to discuss the attacks.
The multiple attacks have ”all the hallmarks of a structured and timed terrorist attack”, a security expert told the BBC.
Roy Ram said although there is no evidence yet that the mayhem was caused by terrorists, it is ”very difficult to think it is any other than deliberate human action”.
Reports said people with their faces covered in blood and soot emerged from underground stations in central and north London.
Hayley Mathie, a South African sub-editor working in London, told the Mail & Guardian Online: ”There are police everywhere and continuous sirens.
”They initially said it was a power surge on the tube, but the bus explosions have knocked that theory out of the water. All tubes are closed and they’ve told everyone in central London to stay inside.”
Indressa Naidoo, a BBC employee, told the M&G Online: ”All I can say is that it is absolute chaos. And if people have been wondering how London is going to cope with any kind of attack, they will find out today.”
Another South African in London, Amanda Killick, who works for Citigroup, told the M&G Online: ”We might be evacuated because of the explosions that have been happening on the underground and buses … Everyone is a bit scared, quite a change in mood from yesterday’s Olympic euphoria.”
The chaos came a day after the British capital was chosen to host the 2012 Olympics.
A huge emergency operation swung into action following the explosions.
Scotland Yard said it had received reports of ”multiple explosions” across London.
A British transport police spokesperson told The Guardian that two trains remained stuck in tunnels at Edgware Road, but it is not known whether they had collided or whether passengers remained on board.
Thousands of people have been evacuated from underground trains in a ”calm manner”, police said.
It is too early to speculate about a possible terrorist attack, police said.
Eyewitness accounts
Witnesses on Sky television were quoted as saying people streamed out of some of the stations covered in soot, some in tears, many visibly shocked.
One eyewitness, Darren Hall, said some passengers emerging from an evacuated subway station and that some passengers 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.
Jacqui Head, from BBC News, who had just left King’s Cross station on a Piccadilly Line train as an explosion happened, said: ”Everything was normal. Suddenly there was a massive bang, the train jolted.
”There was immediately smoke everywhere and it was hot and everybody panicked. People started screaming and crying.”
The train was kept in the tunnel for 20 minutes and no announcement was made to explain the delay to passengers, she added.
Another passenger, who had left the Tube at Fenchurch Street station, and walked to Aldgate East, told BBC Five Live that he saw injured people, reported BBC News.
”As I walked through the bus station I could see people lying on the ground, black, as if they’d been covered in smoke. There were about three or four people on the floor being treated.”
Eyewitness Paul Woloszyn from BBC News, who was at Blackhorse Road station on the Victoria Line, said: ”We were told there was a bomb at Liverpool Street station.”
Witness Belinda Seabrook told Sky News she saw an explosion rip though a bus as it approached Russell Square.
”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,” she said.
Another witness, only identified as Angie, told Sky News: ”There were a whole lot of people around the bus. Next thing I was on the floor and there were a lot of people on me.
”I thought I was going to be crushed. The bus was ripped out at the back. It must have been a bomb.”
Rowan Puttergill told the M&G Online from London: ”At first, I wasn’t sure what was happening. The tubes all stopped, the buses were all jam-packed with people. There were police cars and ambulances all over the place … and I started walking in to work. I only found out what was happening when I got in.”