The US Naval Academy in Annapolis, Maryland, was placed under a full lockdown on Friday after reports of a shooting inside Bancroft Hall, the academy’s massive dormitory housing over 1,600 midshipmen.

Officials stated that the incident involved a dismissed midshipman who allegedly returned to campus posing as a military policeman, knocked on several doors, and then opened fire.

Authorities said that one person was injured in the incident and was immediately airlifted to a nearby hospital, where they are reported to be in stable condition.

The Naval Academy, along with local law enforcement agencies, is actively investigating the incident and responding to threats made against the military school.

Lieutenant Naweed Lemar, spokesperson for the base hosting the academy, confirmed that the lockdown was imposed “out of an abundance of caution.” Police officers and emergency responders were seen near Bancroft Hall as search and security operations continued.

The academy noted that Bancroft Hall, considered the largest single college dormitory in the world, remains under heavy security while investigations are ongoing.