At about 8.45am — nearly the same time as the first of the twin towers in the US was attacked on September 11, 2001 — Aldgate underground station in East London was rocked by a loud explosion.
Moments later black smoke came streaming out of the station concourse, which unlike most tube stations has its platforms at ground level.
I saw from my window overlooking the concourse dozens of people walking and running from the platform, one with their coat smouldering.
Other eye-witnesses said they saw a man with a badly cut leg helped out of the station; a number of dazed people with black smoke on their faces sat on the ground.
After the explosion and initial rush of people everything calmed down; it took about 10 minutes for all the passengers to be evacuated. Most were walking, appearing to be confused but unharmed.
At about this time the first fire, police and ambulance services arrived and sealed off the station. Police described walking 200 yards down the tunnel from Aldgate and seeing one dead body and another person critically injured.
They said the explosion, which took place in the middle carriage, had caused extensive damage; blood and body parts covered a wide area.
Twenty minutes after the explosion surrounding buildings were evacuated.
Seven-storey Aldgate House is home to Canadian media company Thomson Financial, equity market settlements company LCH.Clearnet, and Marsh McLennan, the world’s largest insurance company, which also suffered staff casualties in the New York terrorist attacks in September 2001.
On the other side of the station is the Matrix building, where defence company Thales has offices.
Initially the police cordoning off the area told the public the explosion was caused by an electrical fault, but officers privately told each other that it was a bomb. This was confirmed minutes later as their radios reported further attacks on bus and tube stations.
As this news filtered through, the police extended the cordon; people calmly moved back and followed instructions, waiting and looking. There was no panic.
Police at the scene said the explosions had not come as a surprise to them, and that they thought al Qaeda was probably responsible.
At a pizzeria near to Aldgate station staff handed out tea and sandwiches to police officers while they texted and phoned their own loved ones or watched the television news.
James Mawson was on the scene of the first explosion