Archie Washington Lucas, 63, of Akron was treated at UPMC Horizon, Farrell, a hospital spokeswoman said. Police said Lucas was wearing his seatbelt when the accident occurred at 5:47 p.m.

Police said Lucas lost control of his eastbound rig, which was towing two trailers, on the ice-covered road. The tractor-trailer slid off the left berm, hit the guide rail and continued across a 150-foot bridge until it hit another guide rail. The rear trailer rolled onto its side and caught fire, police said.

The trailer was hauling a hazardous material, tert-butyl hypochlorite, which was released into the air through smoke from the fire, police said. Residents living on Habarka, Wheatland-West Middlesex, Elliot and Sieg Hill roads and East Paul Street in Shenango Township were evacuated until the smoke cleared. Residents were allowed to return to their homes at about 9:30 p.m.

Paul Saternow, a safety and environmental consultant who owns Safety Dynamics of Lowellville, Ohio, said the precautions were taken because the chemical is listed in the emergency response guide book and could cause a potential hazard. Tert-butyl hypochlorite burns rapidly and reacts with water, which is why authorities simply let the chemical burn after it caught fire. Letting it burn meant residents in the immediate area had to be evacuated due to toxic fumes, Saternow said.

More than 24 hours after the spill, state police said Monday night they had no information on the chemical, what it is used for, what company Lucas was hauling for or where he was taking it. Saternow said tert-butyl hypochlorite is not a commonly used material.

The accident closed both eastbound lanes of I-80 between Hubbard and Shenango Township while the fire burned itself out, because contact with water could make the chemical explode. All lanes of traffic were open Monday morning.

Shenango Township volunteer firefighters were on the scene until 5:30 a.m. Monday, Chief Ron Ziglear said.

Also on the scene were township police, PennDOT crews, the Mercer County Emergency Management Agency andy Sheriff's Department and the state Department of Environmental Protection, police said.