FBI arrests Pennsylvania man on terrorism charges in alleged connection with ISIS

PITTSBURGH (CBS, KYMA) - A 21-year-old Pennsylvania man is facing terrorism charges in an alleged connection with ISIS.

Authorities said Jonathan Kramer of suburban Pittsburgh pledged allegiance to the Islamic State of Syria and armed himself to carry out a mass-casualty attack.

He's charged with receiving a firearm and ammunition, knowing or having reasonable cause to believe they would be used to commit a felony or federal crime of terrorism.

An online tip alerted the FBI and Kramer was picked up Saturday, one day after the nation marked 25 years since the 9/11 terror attacks.

According to the criminal complaint, Kramer described in documents methods of mass casualty attacks on schools, nightclubs, theaters, concerts, apartment buildings and synagogues.