MURDOCK (AP) - Authorities say a collision between a Burlington Northern Santa Fe train and a semi carrying anhydrous ammonia injured four people, caused a small leak of the volatile chemical and evacuated a nearby elementary school in western Minnesota.

Swift County sheriff's officials the collision between the train engine and semi happened Tuesday about 8:30 a.m. west of Murdock on Highway 12.  A chemical assessment team was called to secure a small leak of anhydrous ammonia.

Burlington Northern spokeswoman Amy McBeth says three train crew members suffered non-life threatening injuries and the driver of the semi was also hurt. Sheriff's officials say one of injured was airlifted from the scene.

Students from Murdock Elementary were moved to Kerkhoven High School. McBeth says none of the cars of the train, headed for Kansas City, Mo., derailed.