A massive intelligence operation is under way after the series of bomb attacks which killed at least 50 people in central London.
The three bombs on the Tube system exploded "within seconds" of each other, Deputy Assistant Commissioner of the Metropolitan Police Brian
Paddick has told a news conference.
Conditions which the body recovery teams are working under are "extremely unpleasant" said Det Supt Jim Dickie.
Here is a summary of the main points of the inquiry and recovery operation to have emerged.
All three bombs on the London Underground system exploded within 50 seconds of each other at around 0850 on Thursday. Police say that points to the use of timers
No bodies have been formally identified. Autopsies and pathologies were beginning on Saturday afternoon
Police have set up a support centre at the Queen Mother Sports Centre on 223 Vauxhall Bridge Road in London for people attempting to trace missing friends and relatives
Bombs used in the attacks were
made of high explosive - and probably were not homemade, say police
Number of bodies trapped below
London's King's Cross station is not known. Rescue conditions at the station are "extremely difficult," police say. "It is hot, dusty and quite dangerous."
More than 50 people are so far known to have died in the blasts, on three trains and a bus. The bus bomb claimed 13 lives
The first bomb exploded at the Aldgate station in east London. Two more went off within seconds
People from Sierra Leone, Australia, Portugal, Poland and China as well as the UK were caught up in the blasts
Scotland Yard Commissioner Sir Ian Blair said the timing of the attacks meant it could not have been carried out by just one person and there was no evidence it was suicide bombings
London mayor Ken Livingstone said he would be using the tube to get to work on Monday and he urged Londoners to do the same
He praised the work of the emergency services saying: "Everything we had planned for on this day we knew would happen, worked like clockwork."
Some 120,000 calls have been received by the Scotland Yard casualty bureau
The nature of the explosion on the bus is also making it difficult for search teams to be accurate on the death toll, police said
Each device was likely to have contained less than 10lbs of explosives
The devices were probably of a size which would fit into a rucksack, police believe
The Liverpool Street explosion happened 100 yards into a tunnel and the device was in the third carriage of the train.
In the explosion between King's Cross and Russell Square the bomb was in the first carriage
The device in the Edgware Road blast was in the second carriage
It is believed the bombs on the Tube trains were all on the floors of the carriages at the time of their detonation
Sir Ian said police are still not sure exactly where the bomb on the bus was placed
He said there was no proof that the bus bomb was the work of a suicide bomber but at this stage "nothing could be ruled out"
There were two other "controlled explosions" carried out by Met experts on Thursday but no other bombs were found
Police considered suspending the mobile phone network in the wake of the attacks but decided such a move would have damaged public confidence
Early indications suggest the attacks were carried out by al-Qaeda, Sir Ian said
He dismissed reports that the bombings were the work of a terror cell based in the Midlands as "pure speculation"
Investigators are sifting through hundreds of hours worth of CCTV footage from a huge number of locations and collecting forensic evidence from the bomb sites
Metropolitan Police staff have been "overwhelmed" by help from other forces in Europe and the US
Sir Ian said it is "likely" that a terrorist cell is still active in the UK and warned people to be vigilant
"This is a national issue, not just for London. All of the police forces in the UK are taking steps to increase their footsteps on the ground and to work with communities," he said
Anyone with information is urged to contact the anti-terrorist hotline on 0800 789321
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