Students at Murdock Elementary School in west-central Minnesota are expected to return to their classrooms Wednesday after a leak of anhydrous ammonia prompted a precautionary evacuation.
A freight train collided with a tanker truck just west of Murdock Tuesday, causing the tank to rupture and anhydrous ammonia gas to be released.
The truck driver was listed in critical but stable condition at a St. Cloud hospital Tuesday night. Four others also required medical attention.
Swift County Emergency Management Director Bill McGeary says anhydrous ammonia vapors are extremely hazardous.
"What it does is, it attaches itself to moisture. So if you breathe it in it attaches to the mucous membranes and the moisture in your nose and throat, and it virtually paralyzes your nose and throat and breathing," he said.
The accident also led authorities to close a section of Highway 12 for the day.