Two people tried to ram a vehicle through the gates of the US National Security Agency on Monday. US officials say one of the intruders was shot dead and the other was injured.
A senior defense department official says the two men tried to ram their SUV through the gate and were dressed as women.
An FBI spokeswoman says the incident is not thought to be linked to extremism. The agency is working with the US Attorney's Office to determine if federal charges are warranted.
The NSA is headquartered in Fort Meade near Baltimore.