Pinnacle Park, located near the town of the Sylva in Jackson County, North Carolina, is closed until further notice after local authorities realized that someone has been deliberately planting spikes on the park’s heavily used hiking trails.

According to Sylva Police Chief Davis Woodard, a trail runner was impaled by such a spike on February 11. The runner received medical treatment, which included a tetanus shot.

“Someone deliberately put them there,” Paige Roberson Dowling, Sylva’s town manager, told WLOS.

According to Dowling, more than 30 spikes were found over the weekend.

Another visitor to Pinnacle Park had a run in with a similar booby trap on Saturday Feb. 18.

Related: Missing Hiker Found Tied to a Tree Near Blue Ridge Parkway

During this incident the spike apparently entered and exited the hiker’s boot, but did not come into direct contact with his or her foot.

Pinnacle Park—which houses 1,100 acres of protected land formerly used as a watershed for the town of Sylva—features a heavily-used network of trails that lead to the park’s namesake Pinnacle and then all the way up to the Blue Ridge Parkway and the popular viewpoint of Waterrock Knob.

Related: 33 Highlights Along the Blue Ridge Parkway

According to the Sylva Herald, at least 18 miles of trails in Pinnacle Park are being scoured by officials with metal detectors this afternoon.

Chief Davis Woodward said there is a “$1,000 reward leading to the arrest and conviction of the person(s) responsible.”

Individuals with additional information have been urged to contact the Sylva Police Department at (828) 586-2916.