Police are still trying to piece together exactly what happened, but it appears the woman had stopped her car in the right hand lane at about 3.10pm.

The passenger of the car, a 70-year-old man, also from Drouin, was outside the car at the time of the crash and was uninjured.

The driver of the second car, a 20-year-old Ballarat woman, was taken to hospital with minor injuries.

Anyone who witnessed the incident, or who may have dash cam footage of how the incident may have occurred, is asked to call Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au.

UPDATE 6.45pm:

A woman has died following a crash in Gordon this afternoon, Victoria Police has confirmed.

A spokesperson says the Major Collision Investigation Unit is investigating the circumstances surrounding the fatal crash.

Emergency services were called after a car travelling on the Western Highway, near the Chapman overpass, hit a car stopped in the right-hand running lane of the road about 3.10pm.

The driver of the stopped car, a woman in her 50s, received serious injuries and died at the scene.

A passenger in the stopped car, a man believed to be in his 70s, was out of the vehicle when the crash happened and was uninjured.

The driver of the second car, a woman believed to be in her 20s, was taken to hospital with minor injuries.

The exact circumstances of the crash are unknown and the investigation is ongoing.

Anyone who witnessed the incident, or who may have dash cam footage, is asked to call Crime Stoppers on 1800 333 000 or submit a confidential report at www.crimestoppersvic.com.au.

UPDATE 4.50pm: A woman is still being treated at the scene of a multi-car crash on the Western Freeway near Gordon with an air ambulance having just arrived on the scene.

The accident occurred just after 3pm this afternoon.

A person in a second car has been transported to St John of God hospital with minor injuries, however the woman who was trapped remains in the hands of paramedics on the scene.

Her condition was last listed as serious.

UPDATE: A woman has been freed from a car almost an hour after a multi-car collision on the Western Freeway this afternoon.

Ambulance Victoria has confirmed that the woman was trapped for sometime after the collision, but is now in the care of ambulance staff.

An Air Ambulance is believed to be heading to the scene and the woman's condition is understood to be serious.

"Ambulance VIctoria was called to reports of a multi-vehicle on the Western Freeway near Gordon at 3.06pm this afternoon," An Ambulance Victoria spokesperson said.

"Two patients are being assessed, one is moving around and appears to only have minor injuries, the second patient, a female, has been mechanically trapped in the vehicle."

All Melbourne-bound lanes of the Western Freeway have been blocked with motorists encouraged to look for alternate routes. Traffic is currently banked up as far as the Westcotts Road intersection.

EARLIER: EMERGENCY services are on the scene of an accident on the Western Freeway near Wallace this afternoon.

There are reports that one person could be trapped in the vehicle which is understood to have been involved in an incident in the Melbourne-bound lanes near the Chapman's Road overpass.

At this stage it is not known whether there are any injuries, however, some delays can be expected for Melbourne-bound travellers this afternoon and drivers are urged to avoid the area if they can.