Warning: Disturbing footage

A video posted to social media showing passengers screaming at a wide-eyed 21-year-old driver moments before she died in a head-on collision is the focal point of a police investigation.

Shania McNeill, 21, was driving with two of her friends at Berkshire Park in Sydney in the early hours of Sunday before she veered into an oncoming car.

She died in the collision, while her two passengers, 20 and 23, were taken to hospital in stable condition.

The younger of the two was trapped in the wreckage before rescuers could cut her free.

Two people in the other car were also taken to hospital.

Police inquiries into the crash are continuing, with police focusing on footage captured from within the young woman's car.

Disturbing footage

Video taken from the front passenger's seat only minutes before the collision was uploaded to Snapchat and shared to about 50 of the trio's friends.

The Snapchat footage, supplied to 7NEWS.com.au, shows a wide-eyed McNeill behind the wheel with the flash of a phone shining in her face.

Earlier Snapchat videos appear to show the group encouraging McNeill to veer into the opposite lane of traffic.

The passengers returned to social media the morning after the crash to take selfies in their hospital beds.

One pouted with blood running from her nose, and both were wearing neck braces.

Police are also aware of the photos, but will not be including them in a report to the Coroner.

A Snapchat taken by McNiell's passengers from the hospital on the morning after the crash. Credit: Snapchat

'Driving is a privilege'

Police Assistant Commissioner Michael Corboy said driving was a "privilege, not a right" and reiterated the importance of drivers keeping their hands on the wheel and off their phones.

"So far this year we’ve issued over 9000 traffic infringement notices in relation to mobile phone use in motor vehicles," he told reporters in Sydney on Tuesday morning.

"One thousand of those have been for P-plate drivers who are not allowed to have mobile phones at all in the car when they're driving."

Chevron Right Icon 'The question about whether the message is getting through is an interesting one.'

He says he is concerned the message isn't getting through.

"Interestingly, 45 people have been issued twice with (infringement notices relating to) mobile phone use.

"The question about whether the message is getting through is an interesting one."

'Sadly missed'

Tributes have begun flowing for McNeill.

Her aunt Tarsha said she was "one of a kind", in a crowdfunding page for the 21-year-old's funeral.

"You were passionate, loved by many including me and you are sadly missed," she wrote.

"Waiting for you to just come home! I’m devastated," a friend wrote on Facebook.

"You changed and brought light to my life."