It took crews 16 hours to reopen the southbound lanes of Interstate 81 following a Monday night wreck involving three deaths, three tractor trailers, one car and a HAZMAT situation.

Officials say the hazardous material has been identified as a concentrated industrial cleaner made by Eco-Lab. Fourteen pallets of the materials spilled from one of the trucks involved in the crash, hindering cleanup efforts.

HAZMAT crews used water to dilute the material and to make it safe for the environment. It took them several hours to clean the spill.

Officials say Virginia State Police started monitoring the air in the area as soon as they got on scene, because they were not sure what the hazardous material was at the time.

Troopers only knew the material was combustible from a placard on the side of the tractor trailer.

One house near the interstate was evacuated, as were several cars, due to smoke from the fire following the accident.

Scott Gray, Woodstock Fire Department, says, "We had 42 motorists north of the incident that we had to evacuate from their cars, abandon their cars, and we took them to the Woodstock Fire Department Shelter. The Red Cross was able to be there as well."

Once the HAZMAT crews had cleared the scene, Virginia Department of Transportation crews came in to inspect the condition of the road.

At one point, they had to call in additional crews to help, but the southbound lanes were reopened around 3:30 p.m. after the crews deemed the road safe.

"If they were not here actually on the scene, they were manning other stations when all of our other stations were depleted of manpower," says Gray. "They were filling stations so they could answer other calls within the department."

Crews were also concerned about possible damage to a bridge directly over the scene of the accident. However, VDOT representatives inspected the bridge and say it is safe.