Four homegrown suicide bombers, three of them from West Yorkshire, U.K., and none of them previously known to the police, carried out last week's bomb attacks on London, police believe. The hunt is now on for the person who police suspect may have masterminded the bombings and who may have already left the country.
"Normality now will not be the same as normality was before," a senior security source said Tuesday night, reflecting on what looks certain to have been Britain's first experience of suicide bombers. The discovery of a bomb factory in Leeds indicates to the police that there were plans for future attacks.
Four men, between 18 and 30, three of them with West Yorkshire addresses and all of them British, met up at Luton station before boarding a Thameslink train to King's Cross the morning of July 7.
It appears that the four, described by security sources as "cleanskins" -- with no convictions or known terrorist involvement -- reached their rendezvous via two or three hired cars, one of which was located Tuesday at Luton station. Explosives were found in the car, police revealed Tuesday night.
Police were also examining a second car found at the station. It was taken to a storage facility at Leighton Buzzard.
Closed-circuit television film from around 8:20 a.m. July 7 shows the four young men, all with identical large rucksacks similar to those carried by infantry soldiers on their backs. The four appeared relaxed.
"You would have thought they were going on a hiking holiday," said the senior security source, who has seen the footage. It is likely to be released Wednesday.
Police were alerted to the existence of one of the four when his distressed family in Leeds called the casualty bureau hotline shortly after 10 p.m. on July 7. Their son had been traveling to London "with his mates" and had not returned. A family liaison officer was dispatched to be with the family, as was the case for all those believed to have lost relatives in the explosions.
In the meantime, police had found personal documents relating to three young men ages 18, 22 and 30, all from West Yorkshire. A driving license and credit cards belonging to the 22-year-old whose parents were concerned about him were found on the bus that blew up in Tavistock Square. The documents of the 30-year-old, whose body was found at Edgware Road station, were discovered both at the scene of that explosion and at the Aldgate bomb scene, where another of the four dead suspects' remains were found. Police believe that the fourth person's remains and documents may still be trapped in the rubble below Russell Square and are hoping they may find those Wednesday.
On Monday night came the breakthrough police were waiting for -- when the CCTV at King's Cross showed the four young men setting off in different directions.
Police Tuesday raided three houses in the Beeston and Holbeck areas of Leeds and two in nearby Dewsbury just after 6 a.m. in a coordinated operation involving scores of officers from West Yorkshire and the anti-terrorist branch. They later raided another house in the Burley district after evacuating 500 residents from homes nearby and blasting down the door in a controlled explosion.
People who were evacuated in the Burley area were given temporary accommodation as police continued to search an address at Alexandra Grove where a suspicious substance had been found, according to officers.
In Dewsbury, officers carried out a meticulous search at a modern bungalow in a middle-class area, and forensic teams loaded at least one car onto a covered transporter.
At Colwyn Road in Beeston, as police searched a house belonging to the Tanweer family, a car hire firm arrived to collect an overdue hire car. Staff were immediately interviewed by police.
Family and friends of two young British-born Muslims -- whose homes were among the six raided Tuesday -- said they had been missing for several days. Hasib Hussain's parents reported him missing on July 7; his documents were found on the No. 30 bus that exploded at 9:47 a.m. Shehzad Tanweer, 22, of Colwyn Road, has also been missing since last week. His documents, police said, were found in the wreckage of the Aldgate train.
While there was satisfaction within the police and intelligence services that they appeared to have identified a bombing team so swiftly, there were also fears on two fronts: that the finding of more explosives in Leeds indicates that this was not a one-off; and that there could be attacks by far-right groups against ethnic minority communities as it became clear that these were not foreign militants entering the country but homegrown bombers.
Assistant commissioner Andy Hayman of the Met's special operations branch and deputy assistant commissioner Peter Clarke, head of the anti-terrorist branch, announced news of the breakthrough Tuesday afternoon. Tuesday night searches were continuing and police were questioning a relative of one of the four men who had been driven to London.
Now the search will concentrate on the "plotters and planners" who would normally brief and equip a team of suicide volunteers. The normal procedure for such operations, if they involved al-Qaida or one of its related groups, would be for the chief planner to have left the country before the operations took place. There is a possibility that those who planned it are still in Britain. Police are now checking flight records for suspicious passengers.
Clarke said: "I would like at this stage to thank the public for all the support and assistance they have already provided. It is invaluable."
Hayman described those who had perpetrated the attack as "extremist criminals" and added: "It's at times like these that communities bind together ... No one should smear or stigmatize any community with these acts."
There are as yet no indications that any of the four left behind any message about their intentions.
The police are going through 2,500 tapes and evaluating more than 2,000 calls from the public. They have more than 100 witness statements. They stressed Tuesday night that they were at the start rather than at the end of their investigation.