Two people dead after failed train-track rescue tragedy

A woman in her 30s and a man in his 20s are dead after being struck by a train at Berowra station. (Dan Himbrechts/AAP PHOTOS)

An attempt to retrieve an item from the train tracks at a northern Sydney station has ended in tragedy with the deaths of two people.

A woman in her 30s was being helped off the tracks at Berowra station, on the city's northern outskirts, by a man in his 20s when they were hit by a freight train about midnight on Friday, police said.

The pair, who are yet to be formally identified but are believed to have known each other, were treated by paramedics but died at the scene.

Police say the pair had been trying to recover some items from the train tracks, when they were hit. (Dan Himbrechts/AAP PHOTOS)

NSW Police deputy commissioner Mal Lanyon said investigators were still working through the details of what led to the tragedy, but it appeared the man and the woman were trying to retrieve some of their property from the tracks.

"It appears (they) have entered the railway track and, unfortunately, a train approached at the time," he said.

Local police are investigating the incident and a report will be prepared for the coroner.

A crime scene was initially established, but investigators had left the scene by late in the morning.