A firefight erupted Monday when two people in a car tried to ram a National Security Agency gate at the Fort Meade military installation, killing at least one person, according to preliminary reports cited by two US officials.
An FBI spokesperson said the incident was not believed to be linked to terrorism.
The two federal officials said at least one of the people in the car died after the firefight ensued. Both spoke on condition of anonymity because they were not authorized to discuss an ongoing incident on the record.
A senior defense official said the two men were dressed as women. That official also spoke on condition of anonymity because the official was not authorized to discuss an ongoing incident.
The NSA is headquartered on the sprawling Army installation near Baltimore.
FBI spokesperson Amy J Thoreson said in an email Monday that the shooting scene is contained. The agency is working with the US Attorney's Office in Maryland to determine if federal charges are warranted, she said.
Thoreson also says FBI agents are doing interviews with witnesses.
Local television showed two damaged vehicles near a gate and emergency workers loading an injured uniformed man into an ambulance. Aerial news images showed that one of the damaged vehicles was a white SUV marked "NSA Police." Its front end was crumpled, and the hood was up. The other was a dark, unmarked SUV.
A building on the NSA campus was damaged by gunfire earlier this month. Authorities captured a man on March 3 who they believe fired that night on the NSA site, as well as earlier at several nearby places and two moving vehicles. The suspect in that case, Hong Young, told police he heard voices directing him to fire on one of the occupied vehicles.
The gate that serves as the NSA entrance is just off the Baltimore-Washington Parkway, a scenic commuter route. In addition to the NSA, Fort Meade is home to the Defense Information Systems Agency and the US Cyber Command. About 11,000 military personnel and about 29,000 civilian employees work on the property.