Two men have been arrested in the state of Utah on suspicion of setting potentially deadly booby traps - including trip wire and a spiked boulder - along a popular canyon trail.
One of the devices was constructed to trip a ground wire, which would trigger a 20lb spiked boulder to swing at head level.
Another trap was designed to trip any passers-by into a series of sharpened wooden stakes, authorities said.
The traps, discovered by US Forest Service officer James Schoeffler while on routine patrol, were set on the Big Springs trail in Provo Canyon, about 50 miles (80km) south of the state capital, Salt Lake City.
They were thought to be intended for people although the suspects claimed they wanted to trap wild animals.
Benjamin Rutkowski, 19, of Orem, Utah, and Kai Christensen, 21, of Provo, were arrested on suspicion of reckless endangerment.
The two men were accused of building a wooden shelter as a possible lure for hikers, who would have had to pass through booby-trapped entrances to get inside.
Sgt Spencer Cannon said: "This is a shelter put together by people, visited by people - anything that would be impacted by their device would have to be humans.
"It took some time to build these traps."
The hiking trails are popular with families and college students.
"A lot of people go up there after dark as well," Cannon said. "We're very fortunate that it was Officer Schoeffler who found it."
Schoeffler disabled the traps after taking pictures and videoing the site. Police tracked down the suspects after police were alerted to comments on Facebook that mentioned the traps and the shelter.