Two people have died and a man has been arrested following a horror two-car smash that shut down a major highway in both directions.

Emergency services were called to a service station on King Georges Road, South Hurstville, in Sydney‘s south-west, following reports of a vehicle theft on Saturday.

Officers were told a 25-year-old man was allegedly assaulted by a 31-year-old man who then stole his red Toyota Camry and fled the scene.

A short time later, highway patrol officers tracked down the vehicle on King Georges Road in Beverley Hills.

When the car failed to stop, a dramatic chase ensued.

Officers followed the vehicle on the M5 motorway before police said the chase was terminated in Bankstown, with a police helicopter continuing to follow the car.

About 11.10am, the Toyota collided with a cream Alfa Romeo sedan on the Old Hume Highway at Camden South.

The two occupants in the Alfa Romeo both died at the scene, despite the efforts of police officers and paramedics.

Both of the vehicles involved in the crash have sustained significant damage

Police and fire crews were called to the major highway south-west of Sydney about 11.30am

A man was seen being consoled by a witness at the scene following the crash

The man was seen putting his hands on his head at one point

They are yet to be formally identified.

Police said the 31-year-old man was arrested after trying to flee the scene on foot.

He was transported to Campbelltown Hospital for mandatory testing, before being taken Campbelltown Police Station where inquiries will continue.

No charges have been laid.

In footage from the scene, the Toyota Camry and the Alfa Romeo are seen with significant damage, with the Romeo’s windshield completely shattered.

A man was seen being consoled by bystanders at the scene.

A witness told Daily Mail they saw the Toyota Camry driving on the wrong side of the road while being followed by about 4-5 marked and unmarked police cars.

The highway was closed in both directions at the intersection of Camden Bypass, with drivers diverted via Burragorang Road and Cawdor Road.

Motorists have been told to avoid the area.

Emergency responders are seen erecting a Fire and Rescue NSW tent at the scene

Dozens of police officers were at the scene in South Camden on Saturday

The Old Hume Highway is expected to be closed for some time