Pair killed by Sydney freight train were picking up phone thrown onto the tracks

A couple has been killed by a freight train in Sydney's far north overnight, after trying to retrieve a phone from the tracks.

9News understands Aroulen Chinnien and his partner, a woman in her 30s, had got into an argument when the woman's phone was thrown onto the tracks.

She jumped onto the rail line to retrieve her phone, and Chinnien followed to try to push her out of the way of the oncoming train.

READ MORE: Man stabbed, another found lying injured on road in western Sydney

The train was unable to stop in time, striking them both just after midnight.

Police are treating the incident as misadventure.

The pair were treated by paramedics, however, they died at the scene.

They have not been formally identified.

Speaking this morning, Deputy Commissioner Mal Lanyon said it's believed the pair were trying to retrieve something that belonged to one of them, that had fallen onto the tracks.

They are believed to be known to each other.

Rail services between Hornsby and Gosford were suspended for about two hours, but have now re-opened.

Police are investigating the incident.

A report will be prepared for the coroner.