UPDATE: Terrorism suspect appears in court

A Harrisburg man arrested in an FBI raid Thursday afternoon is accused of aiding the ISIS terrorist group, federal court filings show.

Those just unsealed filings charge 19-year-old Jalil Ibn Ameer Aziz of spreading propaganda for the terrorist organization via the internet. Agents also reported finding a tactical backpack, high-capacity gun magazines, ammunition and a "modified kitchen knife" among his belongings, agents said.

MORE: Mayor says public safety was never in jeopardy

He was arrested when heavily-armed federal agents swept down on the 1700 block of Fulton Street in the city's Midtown section around 2 p.m.