A driver involved in a fatal head-on collision on a major highway that left two men dead has been charged with five serious offences while still in hospital.

Emergency services were called to a stretch of the Great Western Highway between Linden and Faulconbridge in the Blue Mountains west of Sydney at about 5.20pm on Wednesday following a collision between a Toyota Camry and Polestar.

The driver of the Toyota, 60, and a backseat passenger in the Polestar, 62, died at the scene.

The men are yet to be formally identified. 

NSW Ambulance spokesperson told Daily Mail Australia that the male driver, 27 and female front seat passenger, 59, in the Polestar were treated for multiple injuries at the scene.

They were taken to Sydney's Westmead Hospital in a serious but stable condition, the spokesperson said, with the woman transported by helicopter.

Following an investigation by Blue Mountains police, officers arrested the male driver at the hospital.

He has been charged with five offences including two counts of negligent driving occasioning death.

Two men were killed after a head-on collision between two cars on the Great Western Highway near Linden on Wednesday night

Two men were killed after a head-on collision between two cars on the Great Western Highway near Linden on Wednesday night

A man and woman were also transported to hospital with multiple injuries

A man and woman were also transported to hospital with multiple injuries 

NSW Police closed the busy Great Western Highway in both directions for more than hour on Wednesday night

It was a nightmare commute home for Blue Mountains motorists

The male driver is also facing two counts of drive manner dangerous causing death and cause bodily harm by misconduct in charge of a motor vehicle.

He was granted conditional bail to appear before Penrith Local Court on April 1.

Two rescue helicopters were deployed to the scene on Wednesday, along with multiple intensive and critical care paramedics and doctors. 

A crime scene was established as police launched an investigation into the circumstances of the crash. 

The crash sparked traffic chaos with the Great Western Highway closed in both directions at Linden for at least 90 minutes.

Footage showed queues of vehicles snaking back for kilometres as emergency services cleared the scene.

'Avoid the area, consider delaying your trip,' a traffic alert stated.

One lane of the highway was opened under stop/slow traffic control shortly before 7pm on Wednesday to allow vehicles to pass the crash site in both directions. 

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