A man fatally shot a U.S. Navy sailor before being shot and killed late last night by responding security forces at Naval Station Norfolk in Virginia, a base spokeswoman said.

Watch Steve Centanni's report above, and read more on the story at FoxNews.com.

Terri Davis says the shooting happened around 11:20 p.m. Monday aboard the USS Mahan, a destroyer. Davis would not describe the circumstances of the shooting but said the scene is secure. 

Davis says the two killed were both males but she didn't have any other information on them. She could not say if the civilian had permission to be aboard the ship or not. No other injuries were reported.

The base -- the largest naval installation in the world -- was briefly put on lockdown after the shooting as a precaution, but that was later lifted. Operations have returned to normal at the base, with counselors available, the Navy said in a news release, but enlisted sailors on the Mahan were not to report to duty Tuesday.

To get on the base, civilians must be escorted or have a pass. Each base entrance is guarded, and all 13 piers have additional security forces.