A veteran long-distance trail runner from Eagan died during a rigorous race over the weekend on the North Shore, officials said Monday.

Jon Mathson, 41, was participating in the Superior Trail Race late Saturday morning in the 25-kilometer (15.5-mile) event, according to the Cook County Sheriff's Office.

Mathson, a science teacher at Eagan High School since 2007, was between Moose Mountain and Mystery Mountain in Lutsen, a few miles from the finish at Caribou Highlands Lodge, when he collapsed, the sheriff's office said.

Resuscitation efforts by medical personnel, four nurses and an off-duty sheriff's deputy, were performed, but Mathson was declared dead at the scene.

Neither the Sheriff's Office nor race organizers had information on what led to Mathson's death.

Mathson, who had completed the 25K race three times previously, "loved trail running and mountain biking with friends, and was an avid birder," a notice on the race's website read. "Jon ... was revered by his students and co-workers alike."

The extremely hilly and rugged out-and-back course traverses the Sawtooth Mountain Range on the Superior Hiking Trail in the far reaches of northern Minnesota. It runs along Lake Superior and crosses white-water rivers and streams while cutting through forests.

"Our hearts go out to the family of Mr. Mathson, the Superior Spring Trail Race community, and our first responders for this shocking and difficult loss," said Cook County Sheriff Pat Eliasen.

Minnesota's trail runners make up a tightknit community, with participants who return often to annual races across the state. Race director John Storkamp said that while he didn't know Mathson well, he knows several of his close friends.

"He was pretty well tied in [among his fellow trail runners], and that outpouring of support is indicative of that," Storkamp said.

The Superior Hiking Trail spring races go back to 2003 and are an offshoot of the popular fall event, which includes a 100-mile race.

Storkamp said runners were the first on the scene after Mathson collapsed, and some of them had medical training.

"He was getting care within minutes of going down," Storkamp said.

A longtime friend and fellow trail runner who was competing in the same race said he knew of no health problems with Mathson.

"He was easily capable of running the distance and enjoying it," said Adam Schwartz-Lowe, who went to college at the University of Minnesota-Duluth with Mathson and was among a group that included Mathson, some of his fellow Eagan teachers who would run this race annually, and other friends. "He spent a fair amount of time preparing for it and looked to us like he was in good shape."

Eagan High School Principal Polly Reikowski said that "Jon would tell you the classroom was his Number 1 priority. He focused on getting kids to feel good about their knowledge in science."

Reikowski said she's heard from many students who "felt so personally connected" to Mathson. "Their comments to me were how they felt loved by him."

Along with coaching the school's Science Olympiad, Mathson also helped supervise the school weight room and "urged kids to try mountain biking and trail running. They knew he liked to do that."

A fundraising page on behalf of Mathson's wife, Becky, and 2-year-old son Dylan has been established.