The FBI and Philadelphia District Attorney’s Office announced the arrest of a west Philadelphia teen in connection with a federal terrorism investigation. The FBI took the unnamed 17-year-old into custody on Friday, Aug. 11. Charges the teen is facing include:

• Weapons of mass destruction.
• Criminal conspiracy.
• Arson.
• Causing/risking catastrophe.
• Attempt to commit criminal mischief.
• Possession of an instrument of crime.
• Recklessly endangering another person.

“The charges we have filed against this individual represent the most serious alleged terrorist activity prosecuted in Philadelphia County court in recent history,” Philadelphia District Attorney Larry Krasner said in a statement. “We intend to pursue full accountability for these crimes and will continue to work vigilantly with our law enforcement partners to protect all of our communities from hateful, ideologically driven acts of violence.”

Krasner said he has every intention to try the teen as an adult. The local U.S. attorney is reviewing the case and hasn’t ruled out federal charges.

FBI Special Agent Jacqueline Maguire said the terrorism investigation revealed the Philadelphia teen had communicated with the global terrorism group Katibat al Tawhid wal Jihad, or KTJ. The group is said to be an affiliate of al-Qaida.

“This individual was also sending and receiving media containing terrorist propaganda and guidance on committing to criminal acts, including how to construct a bomb. The investigation further determined that the individual appeared to be taking steps to travel overseas for the purpose of joining or supporting terrorist activity,” Maguire said on Monday, Aug. 14. “Most concerning, however, was the evidence that he had access to firearms and had purchased items and materials commonly used in the construction of improvised explosive devices. Some of these purchases had just occurred in the last few weeks. Among the items he purchased were tactical equipment, wiring, chemicals and devices often used as remote detonators.”

According to officials, Customs and Border Protection records show 14 international shipments of military and tactical gear to the teen’s address. Maguire said the FBI acted after it determined that “public safety was a risk.”

“The young man who is under arrest is an aspiring terrorist, who was not merely thinking, but was doing things that are deeply disturbing and presented a grave danger to everyone himself, his family, the block where he lived, and frankly, people everywhere in Philadelphia and potentially people around the country or even overseas,” Krasner said.