LISLE, N.Y. – State police say 30 horses have been killed when the tractor-trailer hauling them to a rendering plant in Canada caught fire on an upstate New York highway.

Troopers say driver Clarence Phelps of Watertown told police he saw flames coming from the passenger side of his truck around 8 p.m. Monday as he traveled north on Interstate 81 in the town of Lisle, 15 miles north of Binghamton.

Phelps pulled over and tried unsuccessfully to put out the flames. Officials say that when troopers arrived, the vehicle was engulfed in flames. Firefighters put out the blaze.

Troopers say the horses were being taken from Shippensburg, Pa., to a rendering plant in Massueville, Quebec, near Montreal.

They say the fire apparently started when a passenger-side fuel tank malfunctioned.