Gunfire has rung out at the gates of the US National Security Agency (NSA) near Washington after a car tried to drive onto the site of the secretive government body before crashing into a concrete barrier.
- Three people taken into custody
- FBI says no links to terrorism
- At least three people injured
Three people were taken into custody but the FBI said the incident had no links to terrorism.
The motorists, who were not identified, drove the vehicle to a gate of the NSA in Fort Meade, Maryland, shortly before 7:00am.
Armed guards fired on the vehicle after it violated NSA security rules, officials said, injuring at least three people, including the driver.
"There is no indication to think that this is anything more than an isolated incident," said Gordon Johnson, the Federal Bureau of Investigation's special agent in charge for Baltimore, told a press conference.
"We have no reason to believe that there is any nexus to terrorism."
The vehicle had what appeared to be bullet holes in its windscreen and extensive front-end damage after crashing into a concrete traffic barrier, according to video of the scene.
"It looks like the gunfire was directed onto the vehicle," Mr Johnson said, declining to say if weapons were found in the car.
No-one appeared to have been shot, he said.
Two of the people arrested were in the NSA's custody while the third, the driver of the vehicle, had been taken to a hospital with undisclosed injuries, Mr Johnson said.
An NSA police officer and a civilian bystander also suffered injuries that were not life-threatening, he said.
The NSA, one of the US Government's main spy agencies, is headquartered at a US Army facility about 50 kilometres north-east of Washington.
The base is also home to the US Cyber Command and Defence Information School.
The National Security Agency/Central Security Service focuses on using technological tools, including the monitoring of internet traffic, to spy on adversaries.
A White House spokeswoman said President Donald Trump had been briefed on the shooting.
Mr Johnson said it was not clear why the three men had tried to drive onto the site.
Fort Meade is located just off a major Washington-area highway and motorists occasionally unintentionally take the exit that leads them to its gates, which are manned by armed guards.
In March 2015, two people tried to drive through the NSA's heavily guarded gate.
Officers shot at the vehicle when they refused to stop, killing one of the occupants.