A 19-year-old woman was allegedly kidnapped and tortured for six hours before being thrown from a 20-metre bridge in Sydney's west.

Kayla Kendrigan was allegedly thrown from the Windsor Bridge into the Hawkesbury River with her legs and arms tied on Sunday morning but managed to swim to the banks and call for help.

The Campbelltown woman, who was born without her left hand, told police she had been held against her will by a group of people the night before.

Kayla Kendrigan was allegedly thrown from a bridge on Sunday morning. (Supplied)

Matthew Leuthwaite is among four people charged with attempted murder. (Supplied)

The woman managed to swim to the river bank and was later taken to hospital for treatment. (Supplied)

Four people - 19-year-old Brooke Browne, 22-year-old Matthew Leuthwaite, a 16-year-old boy and a 17-year-old girl - have now been charged with attempted murder and a raft other serious offences over the incident.

Ms Kendrigan was allegedly taken from Ambarvale at 8.30pm on Saturday in the boot of a car before being tortured at a Whalan property.

Police allege she was bound with an iPhone cord, bashed with a bat, stabbed, and burned by the group before being blindfolded and thrown into the river.

Video has since emerged that allegedly shows Ms Kendrigan being taunted and held against her will.

In the clip, a woman is tied to a chair while one of her alleged attackers yells at her.

"This is the gronk that wants to call people dogs, now she's tied up in a room like a c---," one person in the video can be heard saying.

Video has emerged of the alleged kidnapping and torture. (9NEWS)

A 17-year-old girl and 16-year-old boy, who cannot be identified, are also charged with attempted murder. (9NEWS)

Brooke Brown was refused bail in court. (Supplied)

Ms Kendrigan's father Ian took to Facebook, saying his daughter is "lucky to be alive".

"I'm an emotional mess at the moment," he wrote.

"I can only be there for my beautiful daughter ... it's in the hands of detectives."

A woman was allegedly thrown 30m from Windsor Bridge into the Hawkesbury River last weekend. (Supplied)

Police arrested Ms Browne and the 17-year-old girl on Tuesday and they were charged with charged with attempted murder, aggravated kidnapping, wounding a person with intent to cause grievous bodily harm, and robbery with wounding.

Mr Leuthwaite attended Windsor Police Station a few hours later and was charged with attempted murder, detaining for advantage in company, aggravated robbery and wounding a person with intent to cause grievous bodily harm.

Ms Browne and Mr Leuthwaite were refused bail in Penrith Local Court today and will appear in the same court in November.

A 16-year-old boy was arrested at a Wallacia home yesterday and later charged with attempted murder, detaining in company with intent to get advantage, occasioning actual bodily harm, aggravated robbery, and wounding a person with intent to cause grievous bodily harm.

The girl and the 16-year-old boy were refused bail and will appear before a Children’s Court.