South West Train services are currently experiencing delays due a person hit by a train on the morning of Tuesday (May 24).
Routes affected are between Reading, Hounslow , Twickenham, and London Waterloo. The disruption is expected to continue until 4pm.
A spokesman for British Transport Police (BTP) said: "We were called to St Margarets station in Twickenham at 10.15am on Tuesday (May 24) to reports of a person being struck by a train.
"Colleagues from Metropolitan Police Service and London Ambulance Service also attended, and a person was pronounced dead at the scene.
"The person's death is not being treated as suspicious and officers are now working to identify them and inform their family.
"A file will be prepared for the coroner."
Passengers told getwestlondon of the scenes immediately after the collision, including members of the public on the platform at St Margarets station coming to their aid.