SAN FRANCISCO (AP) — Video from a helmet camera might reveal what went wrong when two men wearing wingsuits and attempting an illegal cliff jump at Yosemite National Park crashed to their deaths, a park official said.

Footage from the GoPro camera mounted on the helmet of renowned climber Dean Potter shows his friend Graham Hunt hit the ridge first, said Mike Gauthier, the park’s chief of staff.

Potter swooped left, possibly trying to avoid his partner, but he hit the rocks a split second later, Gauthier said.

“It could have been an evasive maneuver,” Gauthier told the San Francisco Chronicle in a Tuesday report (http://bit.ly/1Bac3v5). “Someone else said they saw a clipped piece of a tree up there, so we don’t know for sure.”

The two men jumped at dusk Saturday from Taft Point, 3,500 feet above the valley floor. They wore batlike suits designed to glide them downward from the cliff face at 100 mph.

They were trying to maneuver through a notch in a ridgeline when they hit the rocky outcropping. The men died instantly, and their bodies were found 50 yards apart.

Park officials are using footage from Potter’s helmet camera, along with video and photos from observers, to re-create the accident, the newspaper reported. Potter’s girlfriend, Jenn Rapp, shot video of the launch and heard two impact sounds, Gauthier said.

Potter, 43, and Hunt, 29, were experienced in the extreme sport of wingsuit flying, a more dangerous offshoot of BASE jumping — parachuting off buildings, antennas, spans such as bridges and cliffs. It is illegal in all national parks, and jumpers who are caught are fined and have their equipment confiscated.

At least five people have died in BASE jumping accidents in national parks since January 2014, including the most recent deaths at Yosemite, said Jeffrey Olson, a National Park Service spokesman. Potter and Hunt’s deaths remain under investigation.

“In this sport, you have a fraction of a second to make a life-or-death decision,” said Tom Evans, a Yosemite photographer who writes about rock climbing. “Just one instant of inattention is all you need.”