The United States Naval Academy in Annapolis, Maryland, was placed on lockdown Thursday evening after reports of a person with a firearm allegedly knocking on doors while pretending to be a military officer and gunshots were heard on campus, academy officials and media outlets said.

"Naval Support Activity Annapolis, in coordination with local law enforcement, is currently responding to reports of threats made to the Naval Academy," a Naval Academy spokesperson said in a statement Friday. "The base is on lockdown out of an abundance of caution. This is a developing situation, and we will provide updates as they become available." Students, staff and faculty were advised to shelter in place.

Multiple sources told Fox News that they heard gunfire and that an expelled former student allegedly entered the campus with a gun. Local law enforcement agencies, including Annapolis police, were reported to be conducting a search of academy grounds Thursday night. The Naval Academy and Pentagon did not immediately provide additional public comment, and local authorities said the situation remained under investigation.

The lockdown comes amid a string of threats to college and university campuses following the high-profile assassination of social media influencer Charlie Kirk earlier this month, which prompted heightened security and precautionary measures at some institutions. Officials did not say whether Thursday's incident was connected to other threats or to the assassination, and investigators were working to establish a motive and timeline.

As of the latest statements from academy officials, there were no confirmed reports from authorities of injuries or fatalities. The academy characterized the response as precautionary and said updates would be provided as more information became available. Several news organizations and local outlets reported on-the-ground accounts from students and staff describing officers and emergency personnel moving through campus during the lockdown.

Naval Support Activity Annapolis and Annapolis police have asked that members of the public avoid the area while the response continues. The U.S. Naval Academy and local law enforcement urged anyone with information to contact investigators. The situation remained fluid late Thursday; officials said they would release additional details when verified.