HAGERSTOWN, Md.—Maryland State Police say two men were seriously injured when their tractor-trailer drifted off Interstate 70 and rolled down an embankment.

It happened about 8:40 a.m. Thursday at Sharpsburg Pike south of Hagerstown. Troopers say 57-year-old Richard McKinney of Sharpsville, Pa., was driving a tractor-trailer hauling dog food when it drifted off the road.

Police say the vehicle hit a bridge abutment and guardrail, crossed the off-ramp onto Sharpsburg Pike, drove through more guardrail and rolled 60 feet down an embankment.

McKinney and his son, 27-year-old William Taylor, who was a passenger, were trapped in the vehicle. After being extricated, they were flown to Shock Trauma in Baltimore.

The load of dog food plus 200 gallons of diesel fuel were spilled onto the road.

The accident is under investigation.