A sailor was killed by a civilian shooter at Naval Station Norfolk in Virginia late last night, according to the U.S. Navy, which also reported that Navy Security Forces shot and killed the civilian suspect. 

The incident took place on the destroyer USS Mahan at around 11:20 p.m. and caused a 45-minute lockdown on the Navy station. The Navy reported that no other injuries were sustained, though Navy personnel were aboard the ship and on the pier at the time of the shooting. 

Spokeswoman Beth Baker said the Navy is investigating the shooter's "access and credentials." The shooter somehow managed to carry a firearm onto the world's largest naval base, violating rules that allow only security personnel to carry weapons. Few other details have yet been reported so far, but we know that the sailor killed was on active duty and both the sailor and shooter were male. No motive has yet been determined, but an investigation is underway. 

According to a post on the Naval Station Norfolk's Facebook page, "For USS MAHAN – officers, chiefs and duty section personnel ONLY. Non-duty section enlisted personnel should NOT report." The post added that "counselors from Navy Fleet and Family Service Center are on hand to assist personnel."

The event comes months after a shooter killed 12 civilian workers in the Washington Navy Yard, in September of last year, and a month after an active-shooter drill at the Norfolk base.