New South Wales Police are investigating a Snapchat video of a young Sydney driver, allegedly filmed before she was killed when her car crashed into oncoming traffic.

Shania McNeill, 21, was behind the wheel of a Suzuki Beleno that was travelling on Richmond Road at Berkshire Park – in Sydney’s west - about 1.15am on Sunday when she lost control of the vehicle and hit a Nissan Micra.

Two of Ms McNeill’s female passengers in the car, aged 20 and 23, were taken to Westmead Hospital in a stable condition after the horror crash, however the 21-year-old died at the scene.

A shocking Snapchat video has emerged from the moments before a car crash in Sydney's west that killed 21-year-old Shania McNeill. (Snapchat)

In the video, posted to a social media account and shared up to 50 times, Ms McNeill can be seen driving with a bright light shining in her face while her friends scream her name.

The crash was so serious, Ms McNeill’s 20-year-old passenger was trapped in the vehicle for some time and had to be cut free, and the two people travelling in the Micra – aged 61 and 39 – were also both taken to hospital.

After that incident, another photo that was shared to social media showed the two surviving passengers who were in Ms McNeill’s car posing for a selfie from their hospital beds while wearing neck braces.

The images come after seven people died on roads around NSW over the Anzac weekend, sparking renewed warnings from police for motorists to take more care while driving.

“Driving is a privilege, not a right and there were some people we detected across the holidays who need to accept this and know they will be held accountable for their actions,” Assistant Commissioner Michael Corboy said in a statement yesterday.

This morning, ass. comm. Corboy told Today that the trend of using video chats or video-based social media platforms while driving is a growing trend in places like the United States and police in Australia are trying to stop it before it becomes popular locally.

"It's not just young people - it's right through the (age) spectrum," he said.

Ms McNeill's friends, who were also in the car during the collision, posted this selfie from their hospital beds just a day after the incident. (Snapchat)

"Any trend of going to video or Instagram or any of those social media platforms and sending out video or taping while you're driving is a trend we're really trying to stop.

"The message needs to get through that if you continue to do this, you or your friends could continue to die."

At a press conference later this morning, he launched another appeal for motorists to avoid taking mobile phones into their cars.

"So far this year we’ve issued over 9000 traffic infringement notices in relation to mobile phone use in motor vehicles," he said.

"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.

"Interestingly 45 people have been issued twice with mobile phone use. The question about whether the message is getting through is an interesting one. Nearly 50,000 people were given tickets for mobile phone use last year.

"We will continue to enforce this, we will continue to send the message that we won't be putting up with it, however the message needs to get through to the community.

"It needs to get through to those people who are driving motor vehicles, to the passengers in the car and everyone else that this is unacceptable."

He also said that the video taken while Ms McNeill was driving, as well as the hospital images, will form part of the police investigation into the fatal crash.

"Our thoughts go out to that family - it must be terrible to watch that video and see that in the newspapers this morning," he said.

"We really are calling on all witnesses or anyone who's got dash cam footage to give it to police."

Across the state, 145 major crashes and more than 7300 traffic infringements were recorded by police between April 24 and April 28.