Alexander P. Osborn of Casper died on Thursday from injuries he suffered in a two-vehicle accident on Interstate 25 about eight miles south of Kaycee, according to a press release from the Wyoming Highway Patrol.

Osborn, 53, was driving on an uphill grade southbound on I-25 in a 2007 Kenworth tractor trailer/tanker combination, which was pulling a pup tanker trailer, according to the Highway Patrol.

His rig's two tankers were carrying hot road oil.

Osborn was following Father John Boydston, 68, who was driving a two-door 1983 Oldsmobile pulling a 16-foot, single-axle house trailer.

For unknown reasons, Osborn drove into the rear of Boydston's combination, according to the Wyoming Highway Patrol. The impact caused the drivers to lose control of their vehicles, which went off the highway's west side and down a 20-foot ravine.

Osborn's rig rolled one-fourth onto its driver's side. The pup trailer remained on the highway, but also rolled by one-fourth and came to rest on the bridge deck over the south fork of the Powder River.

Osborn was taken by helicopter to the Wyoming Medical Center in Casper where he later died. Boydston, who lives in Springfield, Colo., was taken by ambulance to the hospital for treatment of his injuries, according to the patrol.

Both drivers were wearing seat belts.

Troopers estimated about 4,500 gallons of the road oil leaked from the tanker compartments. The oil was about 800 feet from the river.

Both lanes of southbound I-25 were closed for about 1 1/2 hours during the investigation and cleanup.