Car hits parked trailer in fatal NSW crash

Emergency services are working to free the body of a man who died when he crashed his car into a parked trailer in Sydney's west.

The man, whose age remains unknown, was found dead inside the wreckage of his vehicle about 6am on Monday on Hassall Street in Smithfield, police say.

The man was the only person in the car. The road is expected to be closed for three to four hours, a police spokeswoman told AAP.