ONTARIO, Calif. -- A truck driver was shot and killed in San Bernardino County by two men believed to have been hitchhikers or possible carjackers, police said.

The shooting happened around 11:30 p.m. Tuesday while the driver was attempting to get onto the westbound 10 Freeway at Milliken Avenue in Ontario, according to Sgt. Robert Freire of the Ontario Police Department. The semi-truck crashed on the on-ramp following the attack.

The driver crawled out of the cab and told police he had been shot in the chest, Freire said. The two male suspects fled on foot. It's believed the men were possibly robbing the driver at the time of the shooting. It was not known what type of cargo the truck was hauling.

The 52-year-old driver was transported to a nearby hospital where he was pronounced dead, Freire said. His identity was not immediately released.

Ontario police say both suspects have been taken into custody after a thorough search of the area.

The Milliken Ave. on-ramp was shut down for hours while police continued their investigation.

Anyone with information is urged to contact Detective Roger Planas or Ontario Police Dispatch at (909) 986-6711. Callers wishing to remain anonymous may contact the We-Tip Hotline at 1-800-78-CRIME. Information can also be left on the We-Tip website at www.wetip.com.