Editor’s note: This story has been updated as more information was received about the fatal incident.

A pair of spring vacationers from Illinois died in a sledding accident Sunday night at Copper Mountain Resort, according to the Summit County Sheriff’s Office.

The Summit County Sheriff’s Office responded to the scene around 8:35 p.m. Emergency medical services treated the two boys, but they could not be revived and were pronounced dead at the scene.

The 17- and 18-year-old boys reportedly rode tandem down the halfpipe and launched off a large snowbank at the bottom before coming down hard on ice, causing blunt force trauma. Summit County Sheriff Jaime FitzSimons said in a phone interview that the boys were on plastic sleds. He said a witness immediately called 911 to report the incident and that an investigation remains ongoing.

“Our thoughts and condolences go out to the families and the friends of the individuals involved in this tragic incident,” FitzSimons said.

Sledding at Copper Mountain is prohibited everywhere except in the designated sledding zone at the Green Acres Snow Play Area from 9 a.m. to sunset, according to Loryn Roberson, a spokesperson for the ski area. The lack of basic safety features on most sleds, including the ability to brake, steer, or stop make them unsafe for use on the ski slopes, Roberson said.

Ski lifts were closed at the time of the incident. Located close to the bottom of the slope near Center Village, the Superpipe — where the incident occurred — was closed and roped off at the time, she said.

“The entire team at Copper Mountain is deeply saddened by this tragic incident,” Dustin Lyman, Copper Mountain’s president and general manager, said in a statement. “Our most sincere condolences go out to the affected families and friends. We are also thankful to our local emergency responders, for their quick response and the medical assistance provided.”

The Summit County Coroner’s Office has taken over the investigation into the cause and manner of death, the release states. The Sheriff’s Office said it would like to remind everyone to be safe while recreating on the snow and to be aware of the risks associated with such activities.

The two boys were seniors at Prairie Central High School in Fairbury, Illinois, according to an email from the school district’s superintendent, Paula Crane.

“Both were great students, talented athletes, and most importantly amazing people,” Crane said. “They were role models for all who knew them, especially our young athletes throughout the district. The Prairie Central Community continues to mourn their loss and will support their families, our staff members and our students throughout the grieving process.”