UPDATE 5pm: The highway will remain closed to heavy vehicles until well into the evening.
Heavy machinery is being used to remove the vehicles that were involved in the crash.
While one lane of the highway is open to cars and light vehicles, delays are still expected.
Drivers are advised to delay their journeys.
UPDATE 4.30pm: Police believe the deceased, who were travelling in the car, were from the Northern part of the state.
The 90s-model Ford Falcon was travelling north when it veered into the path of a south-bound log truck.
The truck driver has not sustained any physical injuries.
UPDATED: Two people have died as a result of the crash. Police have confirmed the crash was between a car and a truck.
Lengthy traffic delays are expected.
EARLIER: The Midland Highway is blocked after a crash near Ross this afternoon.
It is about 10 kilometres south of Ross, near the Mona Vale turn-off, and has blocked the highway
Police say the crash was reported about 1.30pm.
MORE TO COME