Horror Crash Leaves One Dead, Others Trapped Causing Traffic Chaos On Motorway

Sydney's M4 motorway has been thrown into chaos during peak hour after a fatal nine-vehicle crash.

Just before 6am on Thursday eight cars and a truck were involved in a crash at the Church st off-ramp near Mays Hill.

A tradesman aged in his 30s has died, and it remains unclear how many have been injured.

The young man was traveling to work at the time.

Emergency services are still working to free trapped occupants, NSW Police said.

All eastbound lanes approaching Church St have been closed, as well as the Cumberland Highway, Great Western Highway, Burnett St and Prospect Highway eastbound on-ramps.

One westbound lane is also blocked for emergency vehicles.

Vehicles traveling east are being diverted off the motorway at the Cumberland Highway on to the Great Western Highway. Vehicles can rejoin the M4 at James Ruse Drive.

Image: Steve Hart

"Due to the serious nature of this crash, there is no forecast as to when all lanes will be reopened," police said in a statement.

There are reports of traffic extending for 15km.

Eastbound lanes are expected to be closed "for some time", an NSW Police spokesperson told 10 daily, and all motorists are urged to avoid the area.

"It's a nightmare," the spokesperson said.

More to come.