State police searching for a man accused of killing a state trooper say they found two pipe bombs in the Pennsylvania woods during their manhunt.

Lt. Col. George Bivens said Tuesday the pipe bombs were fully functional and could have been set off by either a trip wire or fuse, but appear to be among items that were hastily discarded.

Thirty-one-year-old Eric Frein has been on the run since Sept. 12, accused of killing one state trooper and wounding a second outside their police barracks in Blooming Grove.

Frein is described as a self-taught survivalist with a vendetta against law enforcement. Authorities believe he's hiding in the thick woods near his parents' home in Canadensis.

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