Both directions on the Great Western Highway has reopened in Katoomba following a car and truck motor vehicle crash at 6.30am on Monday morning.

Traffic NSW reported the highway reopened at 1pm. Diversions have been lifted and traffic in the area is returning to normal.

Three women are reportedly in hospital. A woman in her 30s was taken by road ambulance with burns on her torso and injuries to her legs. A child under 10-years-old was flown to Westmead Children's Hospital in a serious condition. A bystander who helped in the crash was taken to a nearby hospital to be treated for minor burns.

Extensive delays on the Great Western Highway and the Bells Line of Road were a result of the crash.

Police investigators were on the scene from early morning.

12.40PM

One lane of traffic has reopened on the Great Western Highway following a truck and car crash on Monday morning.

Transport for NSW have reported the highway remains closed in a westbound direction.

Drivers are asked to exercise caution and expect delays.

MIDDAY UPDATE

Traffic is backed up on the Bells Line of Road as diversions remain in place for a crash on the Great Western Highway.

On Monday morning before 6.30am, a car and truck collided resulting in a car fire where a woman in her 30s and a primary-school aged girl were seriously injured. They've both been transported to hospital. A bystander who assisted with the crash has also been transported to hospital with minor burns.

NSW Traffic have put diversions in place for vehicles under 19 metres in length. The diversion is via the Bells Line of Road.

MP for the Blue Mountains, Trish Doyle advised people delays of up to 15 minutes should be expected for those using the division.

A planned concreate pour had taken place on the Bells Line of Road before the crash, making the diversion slower again.

Ms Doyle told her constituents over Facebook the pour has finished and concreate barriers have moved to help alleviate some of the congestion.

Police investigators are at the site of the Katoomba crash. Traffic NSW anticipate the highway closure to take some time.

10.30AM UPDATE

A primary-school aged girl is in a serious condition following a truck and car crash on the Great Western Highway at Katoomba on Monday morning, according to a NSW Ambulance spokesperson.

NSW Ambulance reported the girl had sustained serious burns and was airlifted to Westmead Children's Hospital.

One motorist, Mt Victoria local Michael Paag, who was travelling just behind the accident, told ACM that a woman and girl were trapped in the car but were pulled out to safety.

Mr Paag said the scene was "very traumatic".

Fire and Rescue NSW superintendent Adam Dewberry said the vehicle was on fire when crews arrived.

"Passers-by pulled both of the occupants, a lady and a child, out of the vehicle," he said.

"Firefighters commenced emergency medical treatment on the child that was suffering some pretty serious burns."

A woman, in her 30s, who was also in the car has been transported to Westmead Hospital via road ambulance. She suffered minor burns to her upper torso. She also sustained injuries to her legs.

A bystander assisted with the crash, she was taken to the Blue Mountains District Memorial Hospital with minor burns to her arms.

The driver of the truck has been taken to the same hospital for mandatory testing.

As at 10.27am the the highway was still closed in both directions. Ongoing police investigations are expected to take some time. Motorists are advised to avoid the area, use an alternate route and expect delays.

-With Australian Associated Press and the Blue Mountains Gazette

9AM UPDATE

THE Great Western Highway remains closed in both directions near Katoomba after a truck and car crash.

The accident, which happened shortly after 6.30am, occurred near Explorers Road, on the Medlow Bath side of Katoomba.

A motorist, Mount Victoria local Michael Paag, who was travelling just behind the accident, told the Blue Mountains Gazette that a woman and girl were trapped in the car but were pulled out to safety.

Mr Paag said the scene was "very traumatic".

Live Traffic says emergency services, Transport for NSW and the Crash Investigation Unit are on the scene.

The advice is to avoid the area. Police investigations are expected to take some time.

In terms of diversions, eastbound motorists (travelling towards Sydney) are being sent via the Darling Causeway and Bells Line of Road and the Northern Road to join the M4 Motorway.

Westbound motorists travelling between Sydney and Lithgow are being sent via the Northern Road or Castlereagh Road to Richmond to join Bells Line of Road, Darling Causeway (for Mt Victoria) or Chifley Road to rejoin the Great Western Highway.

Westbound motorists in the Blue Mountains can use Hawkesbury Road, Springwood Road, Bells Line of Road, Darling Causeway (for Mount Victoria) or Chifley Road to rejoin the Great Western Hwy.

This diversion is not suitable for B-doubles (exceeding 19 metres in length), which are being parked.

EARLIER

The Great Western Highway is closed due to a truck and car crash on Monday morning.

The incident took place at 6.37am on the highway near Explorers Road at Katoomba according to Live Traffic NSW.

Emergency services are at the scene.

Motorists are advised to avoid the area, expect delays and use an alternative route.

The details of the crash are currently unknown.