Dubbo Crash Victim Rescues Niece From Wreckage

An injured man has saved his two-year-old niece just moments after being freed from the wreckage of a deadly crash in North Dubbo.

The accident took place in a roadworks zone at about 12.30pm yesterday, with the semi-trailer hitting vehicles halted on the Newell Highway about 20km north of Dubbo on the road to Gilgandra.

Seven vehicles were involved in the collision: the semi-trailer, a B-double, four sedans, and a utility.

A man and woman aged in their 20s died at the scene, while ten others were injured; among them a two-year-old girl named Jalirah who was travelling with four other members of her family.

Her uncle told 9NEWS that he freed the youngest crash victim just moments after being saved from the carnage himself.

"As I got out I heard bub crying," the man said. (9NEWS)

“I was pulled out by a passer-by. As I got out I heard bub crying,” he said this morning.

“I grabbed her out, then tried to get the other passenger and the driver. But I wasn’t able to grab them because they needed to be cut out.”

Jalirah, who suffered cuts and bruises, has since been released from hospital.

Her mother remains in Dubbo Base hospital in a stable condition, while her sister suffered critical spinal injuries and is being treated in Royal North Shore Hospital.

A timeline of yesterday's deadly accident. (9NEWS)

Two people were killed in the the collision. (9NEWS)

The other victims continue to recover in hospitals in Dubbo and Sydney, including Westmead Hospital and Liverpool hospital.

The Newell Highway closed in both directions overnight amid police investigations, but has since been re-opened.

“Local diversions have also been lifted,” NSW Transport Management Centre said in a statement.

NSW Ambulance superintendent Kathy Golledge earlier described the collision as “absolute carnage”.

“One car is believed to be completely crushed under a truck,” she said.

Up to nine ambulance units and three helicopters were among the emergency responders.

NSW Roads Minister Melinda Pavey yesterday said the scene was one of “total carnage”.

“It is an absolute horror. [The truck] came on to traffic. We had a worker collapse with shock. This is a terrible, terrible crash,” Ms Pavey told the ABC today.

Police said they did not yet know what caused the crash, but implored drivers to be aware of their fatigue levels and to rest when tired.

The Dubbo crash was the third major truck crash on New South Wales roads in two days.

Three people were killed in two separate incidents on Monday.