SUTTON - A tractor-trailer tanker hauling 65,000 gallons of milk rolled over onto its side on Interstate 89 South early Thursday morning, rupturing the tank and spilling an undetermined amount of milk onto the ground.

The crash happened about 3:35 a.m. at mile marker 29.6, between Exits 11 and 10, according to state police.

Frederick Steinhour, 59, of Enosburg, Vt., was driving the fully loaded tractor-trailer tanker truck owned by McDermott's Inc. when he lost control and the truck slid off the left shoulder, rolling onto the driver's side. Steinhour was not injured in the crash.

State troopers from Troop D, Troop G and the Commercial Motor Vehicle Enforcement unit, as well as members of the state Department of Environmental Services, were on scene. Traffic is reduced to one lane in the area of the crash as crews work to remove the truck, which is expected to take several hours.

The crash remains under investigation. State police said one factor being investigated is the possibility the road had iced up since overnight temperatures were hovering around freezing.