Police are searching for a driver they say left the scene of a horror multi-vehicle pile-up that killed a man and left city-bound traffic queued for more than 15 kilometres along the M4 motorway in Sydney's west on Thursday morning.

Ten cars and a light-rigid truck carrying kegs of beer collided about 5.50am on Thursday at the Church Street off-ramp at Mays Hill, near Parramatta.

One person has died in an 11-vehicle crash on the M4. Credit:Nine News

A 36-year-old Wentworthville man, reported to be an Irish national and tradesman on his way to work, was killed when his ute was struck and forced under the cabin of the truck.

Nine patients from the incident were taken to Westmead Hospital, with two still in care.