Shepherd's Bush: 'Someone left a bag and all hell had broken loose'

But only after he stopped his van near the west London station did he realise he was witnessing the immediate aftermath of a serious incident.

Mr Iqbal, 42, said: "There was a man in a blue suit who looked very shaken. He said someone had left a bag in his carriage and all hell had broken loose. He said the man carrying the bag had run out of the station and people ran away from the train. He said he thought he had narrowly avoided being killed."

Police are investigating witness reports that a black or Asian man was seen climbing down a wall beside the platforms, trying to climb a fence to enter gardens, then sprinting towards the BBC Television Centre. The man had been in the last carriage of a Hammersmith & City train heading into central London as it drew into the station at 12.25pm. About 100 people were led from the train in what a witness called a "remarkably orderly" evacuation. Police sources described the incident as an "attempted explosion".

At 10.30pm, press were allowed into an inner cordon within 70 yards of Shepherd's Bush station. A large white tent had been erected into which forensic police teams were driving vans. Police found a second suspicious package in the station. Residents in half a dozen side streets ­ as well as the main road, Uxbridge Road ­ were told they could not return to their homes last night and would have to sleep in a "displaced persons" centre nearby. Unofficial police reports said that there was a bag " located within the station".