Man killed by Sydney train after allegedly vandalising stationary carriage

A man who was killed after being struck by a train in Sydney's south is believed to have been vandalising a stationary carriage just moments earlier.

Police believe the man was killed when he ran across the tracks after defacing the parked train just after midnight, early on Monday.

Early investigations carried out by police suggest the man was vandalising a stationary train moments before his death. Photo: 7 News

The 25-year-old man has not yet been formally identified after emergency services found him dead at Kingsgrove Railway Station.

The train had just left station and was heading south towards Macarthur when it's understood to have hit the man.

It's unknown how the man happened to enter the secured area.

Officers from St George Local Area Command established a crime scene which will be examined by forensic specialists.

The man killed when he was struck by a train at Kingsgrove Station. Photo: 7 News

Investigations into the incident are continuing and a report will be prepared for the information of the coroner.

Police are urging any witnesses to contact Crime Stoppers on 1800 333 000.