DIMMITT, Texas (AP) A fire and explosion at a dairy farm in the Texas Panhandle that injured one person and killed an estimated 18,000 head of cattle was an accident that started with an engine fire in a manure vacuum truck cleaning part of the massive barn, according to state investigators.

A State Fire Marshal report of the April 10 fire at the Southfork Dairy Farm about 50 miles (80 kilometers) southwest of Amarillo did not determine what caused the engine fire, but found there was no intentional act to cause a failure. The April 24 report said the investigation was closed.