BLOOMING GROVE, Pa. >> State police searching for a man accused of killing a trooper said Tuesday they found two pipe bombs in the Pennsylvania woods during their manhunt that were capable of causing significant damage.

The bombs were not deployed, but they were fully functional and had both trip wires and fuses, Lt. Col. George Bivens said at a news conference.

The weapons were among several items that suspect Eric Frein “clearly hastily discarded” at a Pocono Mountains campsite, said Bivens, who then called on the fugitive to surrender.

“You are clearly stressed,” Bivens said. “You are making significant mistakes.”

Frein, 31, has been on the run since Sept. 12, charged with killing one state trooper and wounding a second outside their barracks in Blooming Grove.

Authorities believe the self-taught survivalist is hiding in the rugged terrain near his parents’ home in Canadensis. Bivens said there had been at least one credible sighting of Frein in the past 24 hours, from between 75 yards and 100 yards away through thick woods.

Police said last week they were treating the search area as if it was booby-trapped, because of evidence Frein had been experimenting with explosives.

Bivens said he believes Frein abandoned the pipe bombs because he was “under pressure” from the massive law enforcement presence. Items found with the pipe bombs “conclusively lead us to know they belong to him,” Bivens said, though he declined to identify other objects.

The bombs had the capability of causing substantial damage, Bivens said.

The disclosure comes as deer hunters prepare for bow hunting season to open this weekend. Pennsylvania Game Commission spokesman Travis Lau said that assuming Frein is not captured overnight, hunting would be closed in the area of the search, which is teeming with hundreds of heavily armed law enforcement officers.

Lau said the exact perimeter of the closure has not been finalized.

Hunters have already been asked to keep an eye out for cabins or other structures that look like they’ve been tampered with or used by Frein.

Officers have found several structures where they think the suspect has stayed, Bivens said, and police also know what Frein is eating and drinking. He would not provide specifics.

Bivens said Tuesday that he doesn’t believe this was Frein’s original getaway plan. Frein’s car was found submerged in a swamp several miles from the barracks a few days after the shooting.

“I think things went wrong with his plan,” Bivens said. “I think he at least believed he would have another opportunity to prepare before he went off into the woods, and he didn’t get that opportunity.”

Authorities say Frein has a vendetta against law enforcement and ambushed two troopers during a shift change. Cpl. Bryon Dickson was killed and Tpr. Alex Douglass remains hospitalized with unspecified injuries. Douglass has a long road to recovery, Bivens said.

Dickson wasn’t even supposed to work the night of the ambush, according to Bivens, but was filling in for another trooper. He said there’s no evidence to suggest Frein deliberated targeted the troopers he shot.

–Michael Rubinkam / Associated Press. Associated Press reporter Kathy Matheson contributed to this report from Philadelphia.