A former U.S. Naval Academy midshipman was charged after allegedly sending an online threat that caused mass confusion and led to an hourslong lockdown at the military school last week.

Jackson Fleming, a 23-year-old resident of Chesterton, Indiana, is accused of transmitting a threat in interstate communication, the U.S. Attorney’s Office for the District of Maryland announced on Tuesday. A federal judge approved a complaint containing a single count, which the Maryland prosecutors noted isn’t formal yet. If charged, Fleming faces up to five years in federal prison.

The academy said Fleming attended the school from June 30, 2021, to Jan. 5, 2024.