A person was hit and killed by a Central Line Tube train at East Acton on Tuesday morning.
A British Transport Police spokesperson said the tragic incident occured shortly before 6am.
“Sadly a person was pronounced dead at the scene,” he said. “This incident is not being treated as suspicious and a file will be prepared for the coroner”.
The London Ambulance Service also said it was called to reports of a person hit by a train.
Commuters were initially advised by TfL of severe delays on the line in the wake of the incident, which was later reduced to “minor delays”.
However the line was again suffering severe delays by lunchtime on Tuesday as a faulty train brought more disruption.
The London Overground has no service between Romford and Upminster, New Cross and Surrey Quays, and between Barking and Barking Riverside over the walkout.
A reduced service will operate on all other Overground routes until 6.30pm.
The Elizabeth line has no service between Heathrow/Reading and Liverpool Street to Shenfield because of the strike.
The Bakerloo is also not running between Queens Park and Harrow & Wealdstone due to industrial action, while the District line has minor delays.
A train fault also caused the Metropolitan Line between Chalfont & Latimer and Chesham to stop running on Tuesday morning. The Circle and Hammersmith also experienced minor delays over train cancellations.
The RMT strike means around half of the national network will shut down, with only about 20% of normal services running on strike days. Commuters are being advised to travel only if necessary and check beforehand.