The Wisconsin Department of Natural Resources' Bureau of Law Enforcement and the Osceola Police Department are investigating a fatal snowmobile crash during a safety class in Polk County.

Sarah Thorsland, 13, was killed when her snowmobile suddenly accelerated and hit a loading dock during the riding portion of the safety class at Osceola High School, according to an Osceola police report.

Police say Thorsland received immediate medial attention at the scene and was airlifted to Regions Hospital in the Twin Cities and transferred to Gillette Children's Hospital. She died Sunday afternoon.

Police say she was wearing a helmet. The cause of the acceleration is being investigated by police and the DNR.

“Our thoughts are with the loved ones today," said Conservation Warden Todd Schaller. "We at the DNR also are deeply saddened and troubled by the tragic loss of Sarah. Every facet of this incident is under a joint investigation by the DNR and the Osceola Police Department. We are committed to determine how and why this tragic loss of this life occurred.”

The DNR's Snowmobile Safety Program began in 1972. The program currently has 879 active instructors who are trained and certified to teach by the DNR, the organization sadi. It is believed Saturday’s tragedy was the first fatality or serious crash to occur during any DNR safety class.