( CNN ) -- Authorities hunting suspected cop-killer Eric Matthew Frein say they discovered an AK-47 rifle , some magazines and a small bag of ammo in the northeastern Pennsylvania woods where they believe he was hiding . `` He 's out in those woods right now , '' Pennsylvania Gov . Tom Corbett told reporters Monday morning . He was flanked by State Police Lt. Col George Bivens , who added , `` I do believe that we are close to him at this point . '' Tracking dogs and searchers are indicating `` we 're on the right trail , '' Bivens said Sunday . He confirmed that thermal imaging technology is being used to find 31-year-old Frein , who allegedly killed one state police officer and the shot another officer September 12 outside the Pennsylvania State Police barracks in Blooming Grove . Frein had been planning the ambush for months or possibly years , authorities said . Investigators said the items they found were either abandoned or hidden by Frein , who is a skilled marksman and trained survivalist . Slaying planned for months ? Authorities have said that Frein hated law enforcement and that they believe that he 's solely focused on hurting more officers , but not civilians . A reporter asked Corbett why investigators concluded that . Corbett answered that the night of the barracks shooting , Frein had the opportunity to shoot civilians and did n't take it . As to the rifle that was found over the weekend , it was positioned in such a way that it could be seen , and the items were partially concealed , Bivens said earlier . `` Frein obviously knows we 're there '' searching , he said . Up to 400 law enforcement officers are searching for Frein , including members of the FBI , the U.S . Marshals Service and the Bureau of Alcohol , Tobacco , Firearms and Explosives . They are combing about 200 to 250 square miles of wooded area not far from Frein 's family home in Canadensis -- about 20 miles from where Frein alleged shot state police officers . Hunters should avoid the thick woods , authorities have said . Schools in the areas have canceled classes . Anyone with information or images they believe might be helpful should call 911 or contact law enforcement , Bivens stressed . Bivens also warned that anyone who helps Frein will be charged accordingly .
NEW : Suspect is `` out in those woods right now , '' Pennsylvania governor says . NEW : Authorities use thermal imaging to help them find the 31-year-old survivalist . Investigators discovered AK-47 and ammo they say belong to Eric Matthew Frein . Frein is wanted for killing one Pennsylvania state police officer and shooting another .