Two people died after being struck by a train travelling at 80 mph in Essex on Tuesday, police said.
The man and woman were on the track at Harlow Mill station at about 8 a.m. when the King's Lynn to Tottenham Hale service approached.
The driver of the National Express East Anglia train was approaching the station, where it was not due to stop, when he spotted the pair.
He sounded his horn and applied the emergency brake but was unable to avoid them.
A British Transport Police spokeswoman said: "Just before 8 a.m. this morning ... a train driver reported striking at least one person on the line at Harlow Mill station."
She added the incident was currently being treated as unexplained and a police investigation was under way.
Train services between Cambridge, Stansted Airport and London Liverpool Street station via Harlow Mill have been considerably disrupted by alterations, cancellations and delays.
Buses are being used between Broxbourne, Harlow Town and Bishops Stortford. It is expected the disruption will last for the rest of the day, National Express said on its Web site.
