ASPEN, Colo. (AP) – Carbon monoxide from a camp stove burning in their tent killed a father and son camping near Aspen.

Lightning was initially believed responsible for the deaths of 41-year-old Jeffery Beard and 13-year-old Cameron Beard, both of Colorado Springs. They died near the Maroon Bells on July 16. Authorities later said carbon monoxide poisoning was another possibility and toxicology results released late Monday confirmed that the poisonous gas was to blame.

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Beard’s 12-year-old daughter and 7-year-old son were sleeping in another tent and survived.

Pitkin County coroner Dr. Steve Ayers told The Aspen Times that lightning woke up the girl, who found her father, who had some burns, and brother dead.

“She did the most heroic thing,” Ayers said. “She kept her brother safe at night during the lightning and got him out safely in the morning.”

The girl and her brother ran for help and found other campers.

Bradley Hayek of New Market, Maryland, was backpacking in the area with his family. When the children ran up, one person from Hayek’s group ran to find the bodies, and others escorted the surviving kids down the trail.

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“We didn’t want to have these kids out there too much longer, especially since the weather was supposed to get bad again,” Hayek told The Frederick News-Post.

The roughly 6-mile trek back to the start of the trail included steep terrain and required crossing a few creeks. A helicopter sent to retrieve the bodies of Jeffrey and Cameron Beard hovered overhead.

“It was very traumatic. I felt so sorry for those kids,” Hayek recalled.

The girl and her brother were checked out later at Aspen Valley Hospital and released, Ayers said.

Jeffrey Beard did have burns on his shoulder and face, though that was from somehow getting too close to the stove, which at some point tipped over and went out before causing a fire, Ayers said. The tent was a fully enclosed structure, which likely helped the carbon monoxide to build up, he said.

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