JOHNSTOWN, Pa, (AP) — Authorities say they believe two teenagers arrested on conspiracy and other charges after a trespassing incident at a western Pennsylvania high school may have been planning a shooting at the school.

A 17-year-old Conemaugh Township youth and a 16-year-old Upper Yoder Township youth were charged in Cambria County with conspiracy to commit terrorism and aggravated assault, District Attorney Greg Neugebauer said.

The older teen is also charged with attempted aggravated assault and the younger with conspiracy to commit criminal trespass and a firearms count, he said.

Chief Donald Hess of the Upper Yoder Township police department said five weapons were seized at the home of the younger teen.