Captured on CCTV footage: The homegrown suicide bombers
The men suspected to be responsible for Europe's first suicide bomb attacks were captured on CCTV footage arriving at King's Cross station just before 8.30am last Thursday morning.
Just over an hour and a quarter later more than 50 people were dead including at least two of the men who detonated the bombs, say security sources.
A relative of one of the suspected bombers was arrested following police raids of six homes in Leeds, West Yorkshire, and two cars were seized.
One car parked near Luton railway station, 30 miles north of London, was found to contain explosives, police later revealed.
It is believed the fourth bomber may have joined the three suspects from Yorkshire at Luton.
Police confirmed that one of the four suspects died in the blasts, saying there was forensic evidence he was killed in the Aldgate explosion.
Security sources suspect the three on the tube were suicide bombers but are keeping an open mind on the bus bomber.
The first tube bomb exploded at 8.51am 20 minutes after the suspects were filmed at King's Cross.
Head of the Metropolitan Police anti-terrorist branch Peter Clark described the investigation as "complex and intense".
He revealed documents identifying three of the men were found near three blast sites.
Property belonging to the suspected bus bomber was found in the wreckage and his family in West Yorkshire had reported the man, 19, missing within 20 minutes of the explosion.
A second suspect's property was found at the scene of the Aldgate blast and the belongings of the third man, believed to be 30, was discovered at both the Aldgate and Edgware Road blasts.
"We are trying to establish their movements in the run up to last week's attacks and specifically to establish if they all died in the explosions," Mr Clark said.
Armed officers and bomb disposal experts took part in the raids on six Leeds properties yesterday morning.
At least one controlled explosion was carried out ahead of a raid on one of the homes, where police on the ground said they were searching for explosives.
Local residents said one of the people living at one of the raided homes was 22-year-old Shahzad Tanweer. Neighbours said Mr Tanweer had not been seen for a number of days.
His friend, Mohammed Answar, 19, said he could not believe he could have been involved in the atrocities: "It's impossible. It's not in his nature to do something like this," he said.
The death toll from Thursday's attacks is expected to rise above 52, with police assigning liaison officers to 70 families.
