The main lanes and the service road of the North Freeway at West Road have been shut down as crews tend to the scene.
The accident was reported around 8:45pm on the southbound right shoulder of the North Freeway near West Road.
Police say a 25-year-old man was outside of his truck with his hood up when a red pickup truck struck him from behind. The impact sent the man over the edge of the highway overpass and he landed on the ground about 40 feet below. He died from his injuries.
Detectives say the driver of the pickup truck jumped out of his vehicle and ran, but he was caught by an off-duty deputy nearby. He is now being held on suspicion of drunken driving.
A female passenger inside the victim's disabled car was unharmed.
Police still are interviewing eyewitnesses and investigating the scene of the crash.