A crash at 5.50am today involving multiple cars and a truck on the M4 at Mays Hill near Parramatta has left one person dead, motorists stranded and the morning peak traffic in a mess.

According to Live Traffic Sydney all eastbound lanes and one westbound lane of the M4 remain closed between Cumberland Highway and Church Street, adding, "Anyone needing to travel to the city should consider using the M7 and M2, or catching a T1 Western Line train instead."

Traffic past the Cumberland Highway is being diverted via the Church Street off-ramp. The Prospect Highway, Cumberland Highway, Great Western Highway and Burnett Street eastbound on-ramps to the M4 Motorway have been closed.

The M4 is one of the main arteries leading into Sydney from the west and the fatal crash has resulted in traffic queued for over 15 kilometres to Huntingwood.

The NSW Police says emergency services remain at the scene.

Follow updates here.