A teenager badly injured in a horror car crash that hurt seven people snuck out of bed in the middle of the night, it's understood.

The family of a 13-year-old girl with critical injuries are today at her Christchurch Hospital bedside.

She suffered life-threatening injuries after the car she was travelling in crashed about 17 minutes after reportedly failing to stop for police.

A "suspicious" car with eight people inside it was seen by police travelling through Rolleston just south of Christchurch at 4.22am yesterday.

 

Officers tried to stop the vehicle but it took off, starting a pursuit that was abandoned soon after "due to the nature of driving".

The car was found more than 30km away by police on Bridge St in Rakaia.

It appears the car had struck a fence and rolled.

The Herald understands that the mother of one teenager thought their child had been asleep in bed that night.

However, it's understood they have snuck out in the night to join friends.

The mother only found out she was gone when police phoned with the terrible news in the early hours of the morning.

A spokeswoman for St John said they got the call at 4.39am from police.

Two Westpac rescue helicopters and at least three ambulances were sent to the scene.

She confirmed seven people were rushed to hospital, including two in a critical condition. Four others have serious injuries while another is in a moderate condition.

St John later said one of the injured included a 13-year-old girl in a critical condition. Other teenagers were also injured.

A spokesman for Canterbury District Health Board (CDHB) yesterday said one patient has already been discharged. One is in a stable condition while four have requested privacy. The CDHB said they were unable to get the necessary consent or permission to provide an update for the two other patients at this stage.

A police spokesman said: "Inquiries are ongoing to determine the circumstances around the collision."

The police serious crash unit has completed its scene examination and NZTA said the road had reopened by late morning yesterday.

The tragedy has renewed calls for a ban on police pursuits.

Youth health doctor Sue Bagshaw says it could've easily been avoided, claiming police don't understand that chasing young drivers causes them to panic.

Bagshaw says police need to stop pursuits but overhauling curriculums and tackling poverty should also be on the list.

She says many lower income young people get trapped in a mentality of "live fast now - because you might be dead tomorrow".

A Greymouth mum who lost her son in a police pursuit also said yesterday's smash shows they should be scrapped.

Joe Hall lost her teenage son Judd in 2014 and says the pain never goes away.

She says yesterday's crash will have left eight more families hurting.

Hall says the decision-making centres of teenagers aren't developed enough to understand the consequences.

She says their fight-or-flight response kicks in - and they panic.