Sgt. Barry Montgomery told reporters an on-duty officer was driving the vehicle just after midnight when he accidentally struck the man in the 13600 block of Culver Boulevard.
The officer knew he had struck something, so he returned to the area and searched until he found the man on the side of the road, Montgomery said.
The officer performed CPR on the man and called paramedics, Officer Norma Eisenman said. The pedestrian, whose identity has not been released, was pronounced dead at the scene.
The man appeared to be wearing dark clothing and was walking in the roadway, she said. It was also foggy, Montgomery said.
The department is still investigating the incident.