The three bombs that exploded on the London underground railway were made of high explosives, not homemade material -- and blew up within seconds of each other in a near-simultaneous attack, police said yesterday.
Forensic evidence was still being examined, but the type of explosives suggested a degree of sophistication. The material could have been military or commercial.
"It is high explosive," Deputy Assistant Commissioner Brian Paddick said at a Metropolitan Police briefing yesterday. "That would tend to suggest that it is not homemade explosive, but whether it is military explosive, whether it's commercial explosive, whether it's plastic explosive, we don't want to say at this stage."
He said early analysis suggested that each bomb consisted of a "device in a bag, rather than something that was strapped to the individual."
But Paddick said a suicide bombing was still a "possibility. We are not ruling anything out. We are not ruling anything in."
Police said new analysis of the timing of Thursday's subway explosions suggested they may have been detonated by synchronized timers rather than by suicide bombers. But authorities said the possibility of suicide bombings had not been ruled out.
"A slightly different picture is emerging around the timing of these bomb incidents," Paddick said. "All three bombs on the London Underground system actually exploded within seconds of each other, at 8:50 in the morning."
Officials originally thought that the explosions had occurred in a 26-minute span.
The first bomb exploded at the Aldgate station in east London. Two more went off within 50 seconds, police said.
Forty-nine bodies have been recovered from the bombings on three subways and a double-decker bus that was blown apart near Russell Square in central London.
All the bodies have been retrieved from the bus, but bodies were still trapped in the tunnels at Russell Square in central London. Heat, dust and other difficult conditions were preventing crews from recovering them from the debris, police said.
Authorities had not identified a single body because the remains were so mangled and difficult to retrieve, police said.
"It is a very harrowing task," Detective Superintendent Jim Dickie told reporters. "Most of the victims have suffered intensive trauma, and by that I mean there are body parts as well as torsos."
Dickie said the process was to get under way yesterday afternoon, and that forensics experts would use fingerprints, dental records and DNA analysis to help put names to the bodies.
"No bodies have been identified as yet because as of yesterday we only started to receive bodies into the temporary mortuary," he said. "Autopsies will be starting today. Until that's done, we won't have gathered the necessary information to make the identification process."
Police have made no arrests so far over the attacks, Paddick said.
"We have not arrested anyone in connection with the incident," he said.
Paddick also said police were not focusing on specific suspects.
"We are not looking at any specific individuals at this stage," he told reporters. "We have all our options open we are pursuing but we are not confirming that we are looking for any particular named individuals."
British Prime Minister Tony Blair said yesterday that links to al-Qaeda were likely, but it was not yet clear who was behind the devastating blasts.