Scotland Yard mounted a massive manhunt tonight after bombers set off four near-simultaneous explosions on the Underground and a London bus, two weeks to the day after the suicide bombings of July 7.
Police said only one person was wounded in the bomb blasts or attempted blasts at Warren Street, Oval and Shepherd's Bush Tube stations, and on the top deck of a bus passing through Hackney.
Graphic of the blasts
Sir Ian Blair, the Metropolitan Police Commissioner, said the explosions were "pretty close to simultaneous", although not all the devices had gone off properly and investigators might be able to recover valuable forensic evidence.
He said that the devices used were smaller than the July 7 attacks - in which suicide bombers killed more than 50 people - and there was no sign of any chemical or biological attack.
"The situation is now coming fully under control," said Sir Ian, who added that while there was a certain "resonance" in a comparison between the two attacks, it was still too early to say that the same group may have been responsible.
But the apparent failure of the devices could be a major breakthrough if the devices provide fingerprints, DNA and possible matches to the bombs used on July 7.
CCTV from Underground stations and the London streets, witness statements and descriptions provided by passengers will be a major part of identifying and catching the bombers.
Sir Ian said: "We have recovered a quantity of material which is very helpful. We do believe this may be a significant breakthrough."
Two weeks ago, four suicide bombers wreaked havoc in the London rush hour, also targeting three Tube trains and a bus in co-ordinated blasts. Three of the bombers were Muslims of Pakistani origin from Leeds and the fourth was a Jamaican-born Muslim convert from Aylesbury.
Streets around the three Tube stations were cordoned off after today's attacks, as was University College Hospital, near Warren Street, where armed police reportedly chased a man into the building. Police left the building around 4pm, apparently without making an arrest.
Hours after the blast on the No 26 bus in Hackney Road, East London, a police cordon was keeping locals and a crowd of reporters 400 yards from the scene.
The driver of the bus, Mark Maybank, 38, told his bosses that he immediately pulled over and shouted for everyone to get off the bus when he heard a small explosion and saw smoke. He rushed to the top deck of his vehicle and saw an abandoned rucksack - which police were still examining with caution tonight.
Tony Blair broke off from a meeting with his Australian counterpart, John Howard, to be briefed on the incidents. After chairing a meeting of Cobra, the Cabinet emergency committee, Mr Blair said that he would be resuming his normal schedule - even though a man with a knapsack was arrested at the gates of Downing Street and led away at gunpoint in an incident later described as unconnected with the bombings.
"We know why these things are done, they're done to scare people and to frighten them, to make them anxious and worried," Mr Blair told a press conference. "The police have done their very best and the security services too in this situation and I think we've just got to react calmly."
Sir Ian appealed to Londoners to stay off the transport system, but to go about their normal business. Five Tube lines - the Victoria, Northern, Hammersmith and City, Bakerloo and Piccadilly - were suspended or partly suspended, although shuttle services were organised.
The Scotland Yard chief said he would not give any details of the course of the investigation, which was evolving rapidly. He confirmed that a manhunt was under way, although he said it was not yet clear how many people might have been involved in the attacks.
As commuters faced a difficult journey home, it emerged that St Albans station had been closed due to a security alert, severely disrupting train services to the Midlands.
Londoners were also urged to avoid making long mobile telephone calls, and to use text messages instead if possible, to avoid overloading mobile networks.
Experts were divided on who might have been responsible. Robert Ayers, a security analyst at Chatham House in London, said that that he believed that the same group was behind both attacks.
"All along I've been saying that you had four guys that died [in the July 7 bombings], but the infrastructure that trained them, equipped them, funded them, pointed them at the right target - the infrastructure’s still in place, still here," he told the Reuters news agency.
He pointed out that police had recovered unused explosives from various sites, including a hire car abandoned by bombers at Luton. Police carried out ten controlled explosions on the hire car in Luton station car park before they placed it on a low-loader and took it away.
"One speculation I’ve had all along is that they left those explosives in the car for another group to pick up and carry out a second attack, but when they got there the car had already been taken over by the police, so they have had to cobble something together fairly quickly," he said.
Others however said that the bombs of two weeks ago might have inspired others to copy. "It looks like it may be people messing around, copycat-type stuff," said Dr Shane Brighton, a terrorism expert at the Royal United Services Institute. "The absence of any clear evidence of substantial blasts means that this is on the face of it at the moment not a follow-up attack of the same proportion."
Dr Brighton added: "It may be an attempt by people to cause panic, maybe people with similar ideas or ideological sympathy with the people that did the recent bombings...The nature of the incidents doesn’t appear to be anything like as serious."
Like July 7, three Tube stations and a bus appeared to be involved, and as on July 7 the targets appeared to describe a rough cross-shape on the map of London, with Warren St in the north, Oval in the south, Hackney in the east and Shepherd's Bush in the west.
Victoria Line passenger Ivan McCracken claimed a traveller’s rucksack had exploded on the Tube as it approached Warren Street station, which is just a few hundred yards from King's Cross station.
He told Sky News: "I was in a middle carriage and the train was not far short of Warren Street station when suddenly the door between my carriage and the next one burst open and dozens of people started rushing through.
"Some were falling, there was mass panic. It was difficult to get the story from any of them what had happened but when I got to ground level there was an Italian young man comforting an Italian girl who told me he had seen what had happened.
"He said that a man was carrying a rucksack and the rucksack suddenly exploded. It was a minor explosion but enough to blow open the rucksack. The man then made an exclamation as if something had gone wrong. At that point everyone rushed from the carriage."
Mr McCracken said he smelled smoke but did not see any injured passengers.
Other reports suggested that gunshots were fired as a man ran away from the scene at Warren Street. A witness spoke of hearing a noise like champagne corks popping, which one analyst said could be detonators going off.
Meanwhile at Oval station a woman passenger reported seeing a man with a rucksack struggling with three male passengers, next to a woman and crying baby. She said: "The carriage opened and the man ran away, but they couldn’t catch up with him. As far as I’m aware that person has got away, but I was just trying to find a way out of the carriage and the station."
Marieta Alexis, 40, was near Warren Street when the station was closed. The PA commutes to London from Romford. "London is becoming like Israel or Beirut," she said. "I don’t feel safe. Now when I take the Tube I wonder what will happen. I look at everyone, especially people carrying rucksacks. They aren’t even threatening the big guns, it’s people like you and me who take the Tube and bus. I’m not petrified but I’ve definitely become more cautious."
