A member of Dartmouth College’s ski team collapsed and died over the weekend while competing in a cross-country ski race in Vermont.

Torin Tucker, 20, a junior from Sun Valley, Idaho, was climbing an uphill stretch of a rugged 25-kilometer course in northeast Vermont on Saturday morning when he fell to the ground. He died moments later and did not respond to resuscitation efforts, said Dartmouth spokesman Justin Anderson.

Officials did not immediately release a cause of death.

“We don’t yet know what happened, in part because it was a total surprise,” he said. “There’s no reason this should have happened to a phenomenal athlete, a young man who was in great shape.”

After Tucker collapsed, his teammates withdrew from the competition, Anderson said.

The flag at the Ivy League school in Hanover, New Hampshire was being flown at half-staff in Tucker’s honor on Sunday as news of the incident spread across a campus that is home to 4,200 undergraduates and 2,100 graduate students, Anderson said.

Dartmouth President Phil Hanlon called the death “a heartbreaking loss” in a written statement and urged students, faculty and staff affected by it to speak with a counselor or therapist.

“Many of us are still in shock and incredibly saddened by yesterday’s tragic event,” Anderson said.

An autopsy is likely, pending family approval, said Anderson.

Tucker and other members of the Dartmouth ski team were among hundreds of contestants in a premier nordic skiing marathon based in the tiny town of Craftsbury in the northeastern corner of Vermont near the U.S. border with Canada.

Dartmouth has made arrangements for a memorial service.