A freight train hauling North Dakota crude oil and a tanker truck carrying hazardous material collided Tuesday morning in west-central Minnesota, causing the tanker to leak, forcing a nearby school to evacuate, closing a major highway and leaving five people in need of medical attention, authorities said.

The collision involving a 102-car BNSF train and a truck hauling anhydrous ammonia from a Koch Nitrogen Co. fertilizer terminal occurred about 8:30 a.m. just northwest of Murdock, according to the Swift County Sheriff's Office. Hwy. 12 remained closed while hazmat teams assessed the cleanup and removal of the truck and trailer.

The truck driver was airlifted to St. Cloud Hospital, where he was listed in stable but critical condition on Tuesday night. His name hasn't been released.

There was an "atmospheric release" of anhydrous ammonia that carried over the facility, Koch spokesman Paul Baltzer said. Authorities added there was no immediate concern for the public's safety from the leak.

A truck driver visiting the terminal required medical observation, Baltzer added. Anhydrous ammonia is an important source of nitrogen fertilizer for crops. Improper handling can lead to severe burns to eyes, skin and the respiratory tract.

Three crew members on the three-engine train were taken to a hospital nearby for treatment of injuries and then released, said BNSF spokeswoman Amy McBeth.

All 102 cars were carrying crude from near Minot, N.D., and bound for Missouri, McBeth said. There was no loss of crude, she added.

Kerkhoven-Murdock-Sunburg Elementary School was evacuated, sending students by bus to the nearby high school.

District Superintendent Martin Heidelberger said the 300 or so displaced students were doing well and preparing for a picnic lunch in the high school commons and gym.

"If you were to ask any of them, they'd say they are on a field trip to the high school," he said. The sixth-graders missed out, he added, because they were on a real field trip to the State Capitol.

The truck, owned by a customer of Koch's, had just left the facility and was hit by the train at 60th St. SE. That prompted the Sheriff's Office to close Hwy. 12 in both directions between Murdock and DeGraff as emergency crews worked to stem the leak. The tracks run parallel to Hwy. 12.

The rail crossing is governed by crossbucks and stop signs but no gates, McBeth said, adding that such a setup is typical for this kind of rural location.