BROOKS, Ky. (AP) _ A tractor-trailer rig hauling liquid herbicide burst into flames on a busy highway today after hitting another truck, filling the area with toxic fumes.

About 250 people were evacuated from a mobile home park and other residential areas, authorities said. Shelters were set up at two schools. Aircraft were ordered to stay three miles from the crash site.

The fire destroyed both trucks. It was mostly out by late morning. Traffic on Interstate 65 in this Louisville suburb remained backed up for miles.

Both drivers were injured. A state trooper and a firefighter also were taken to a hospital after breathing fumes.

Jim Long, a spokesman for the Chemical Transportation Emergency Center in Washington, said the 3,800 pounds of the herbicide Organotin was shipped from Elf Atochem of Axis, Ala., bound for PPG Industries of Louisville.