A man has been found dead on railway lines near Blacktown, this morning.
Police said they were called about 7.05am to investigate the circumstances around the man's death.
They said it appeared he had been struck by a train between Blacktown and Doonside stations but they could not say how the man came to be on the tracks.
The accident has caused major delays on services between Blacktown and St Marys o the Blue Mountains and Western Lines.
A crime scene was established and is being examined by specialist forensic officers.
Investigators are also attempting to identify him and notify his next of kin.
The western railway line was closed for a short time, however, trains are now operating again under caution between the area.