British police Saturday night released a picture of the four London bombers being together as they set off on their deadly mission last week.

A security camera captured the four men entering Luton railway station, just outside London, at 07.21 local time on July 7 on their way to the capital. In the photograph, the four men were dressed casually and appearing relaxed, with backpacks on their shoulders, which are thought to contain the bombs which tore through London's transport system, killing at least 55 people.

Three of the bombers were young British Muslims of Pakistani origin, while the fourth was a Jamaican-born Briton. Two of them were teenagers, while the other two were 22 and 30 respectively. Police have taken more than 800 witness statements and received3,500 calls to the anti-terrorist hotline

The Sunday Times reported that one of the four suicide terrorists was scrutinized by the British Security Service, or M15, last year, but was judged not to be a threat to national security.