CANADENSIS, Pa. — Authorities have had no confirmed sightings of the alleged gunman who is accused of a deadly ambush at a police barracks 10 days ago, but they say they have found an assault rifle he was carrying and believe they are hot on his trail in the dense northeastern Pennsylvania woods.

Investigators said Sunday that the suspect they describe as a self-taught survivalist had been planning a confrontation with law enforcement for months, if not years, and they believe he is still armed and dangerous, and possibly concealing himself in self-built bunkers.

Pennsylvania State Police Lt. Col. George Bivens revealed a few more details about the manhunt for Eric Frein, saying trackers have discovered items he hid or abandoned in the woods — including an AK-47-style assault rifle and ammunition they believe he had been carrying while on the run.

“We are pushing him hard, he is no longer safe and I am confident that he will be apprehended,” Bivens said.

Authorities did not yet know if the weapon had been used in the ambush, he said. Still, police believe Frein, 31, remains dangerous, and possibly armed with a .308 rifle with a scope that police said was missing from his family home along with the AK-47.