US Naval Academy in Maryland on lockdown after gunfire reported

The US Naval Academy in Annapolis, Maryland, was placed on a security lockdown on Thursday while military personnel and local law enforcement investigated reports of threats to the installation, the Navy said on the academy's Facebook page.

There was no immediate official word on the nature of the reported threat. But Fox News, citing multiple sources inside the academy, said a former midshipman who had been expelled from the school had returned to campus armed with a weapon.

According to the Fox News report, gunshots were heard inside Bancroft Hall, which houses the midshipmen.

According to the Facebook statement from Naval Support Activity Annapolis, the "base is on lockdown out of an abundance of caution."

 It said Navy support personnel, in coordination with local law enforcement, were "responding to reports of threats made to the Naval Academy."