A woman has died and another has lost her unborn child after a car crash, with police searching for two teenagers involved.

Just before 3am on Sunday, Newcastle police officers saw a Holden sedan allegedly driving dangerously, but did not pursue it due to safety concerns.

A short time later, the sedan was involved in a head-on collision with another car.

A 55-year-old passenger in that car, who was on holiday from India, was found dead. The 28-year-old driver, who was 25 weeks pregnant and reportedly the older woman’s daughter, suffered serious leg injuries.

Police later confirmed the driver’s unborn child had died.

The driver and a passenger of the Holden left the scene before police arrived.

Witnesses said they saw a male and female running from the area.

Two other passengers in the Holden – teenage girls aged 15 and 17 – were treated by paramedics before being taken to John Hunter Hospital under police guard in a serious condition.

Police are searching for the 19-year-old male driver, acting assistant commissioner Paul Dunn said.

“This is a horrible incident [and] what’s occurred is truly tragic,” he said.

“Two women driving around innocently, one has lost their life, one has lost their unborn child.”

Police have urged anyone with relevant footage or information to come forward.

They also wish to speak with a 17-year-old girl believed to be the front seat passenger of the vehicle.

“We do not believe this to be a stolen vehicle, but joy-riding and driving in a dangerous manner is always a real concern for us here in the Newcastle area,” Dunn said.

A critical incident has been declared and a team from Hunter Valley Police District will investigate the circumstances surrounding the crash.

-AAP