Two men have died after running into the path of a train at a rail depot in east London, police said on Saturday.
The pair, aged 19 and 21, were hit by a District Line train near Barking tube station on the Underground network late on Friday.
British Transport Police (BTP) said they may have been part of a gang that fled after being spotted spraying graffiti in a depot shortly before the accident.
It appears that they ran into the path of the train, Chief Superintendent Paul Crowther told reporters. The driver of the train tried to stop.
Other drivers within the depot had reported seeing a group of people who were apparently engaged in graffiti-ing some trains.
Patrolling security guards had spotted this group, but they ran off through the depot.
Our inquiries at this stage are focussed on identifying whether the people who were struck by the train were linked to the earlier sighting within the depot.
The guards were not chasing the gang, Crowther added.