Three people are accused of kidnapping and trying to murder a woman by throwing her off a bridge in Sydney’s north-west.

The 19-year-old victim has been treated in hospital after allegedly being abducted then tossed into the Hawkesbury River on the weekend.

She tells police she was abducted by a group of people the night before, shoved into the boot of a car and driven from Campbelltown to Windsor before eventually being thrown into the river.

She managed to swim to the riverbank for safety.

A Holden Commodore has since been seized by police.

A 17-year-old girl, a 19-year-old woman, and a 22-year-old man have been charged with attempted murder and kidnapping offences.

One of them has already faced court and been remanded in custody.

Two others have been refused bail to appear in court Thursday.