A pregnant teenager was hurt when a knife fight broke out on a rush hour London Underground train.
The girl, 15, was slashed with a meat cleaver by her boyfriend as he tried to fight four youths on a crowded Central Line train on Wednesday evening.
Passengers watched as the fight spilled from the platform at Mile End station, in east London, onto a carriage.
Four youths have been arrested and bailed. The girl received hospital treatment for a wound to her arm.
The four youths had fled with a stolen bag but police were alerted by a member of the railway staff and were arrested on a bus outside the station.
A spokesman for British Transport Police said the victim would not press charges.
He added: "The fight spilled on to a stationary train which obviously frightened other passengers."
Eastbound trains did not stop at Mile End for three hours while forensic teams searched for clues.