A motorcyclist was killed in a crash Friday afternoon in northwest suburban Des Plaines.

First responders were called at 4:15 p.m. to a report of a motorcycle crash in the 2300 block of South Mount Prospect Road, according to Des Plaines police.

Officers found 40-year-old Miguel A. Alfaro lying near the curb with injuries to his head and face, police and the Cook County medical examiner’s office said. He was pronounced dead at the scene at 4:42 p.m.

An autopsy Saturday found that Alfaro, who lived in Des Plaines, died from multiple blunt force injuries of the head, neck, chest and pelvis as a result of a motorcycle colliding with a traffic sign, the medical examiner’s office said. His death was ruled an accident.

A witness told investigators that he was driving north behind the motorcyclist when he saw dust blown into the air and then saw the motorcycle lying on the ground and its driver lying in the roadway, police said. An investigation into the crash was ongoing.