Elderly couple killed in head-on crash in Sydney's south-west

An elderly couple has been killed in a head-on crash after veering into oncoming traffic in Oran Park, in Sydney's south-west.

Police believe the Commodore wagon swerved onto the wrong side of the Northern Road, smashing into the ute, killing the man and woman aged in their 70s instantly.

Both people in the ute had to be cut free, the force of the impact left the front of both cars unrecognisable.

The male driver was taken to Liverpool Hospital via helicopter with severe leg injuries.

The female passenger was taken to Liverpool Hospital by ambulance with chest and arm injuries.

Investigators are trying to determine what caused the elderly couple to veer into the wrong lane.