At least one person has been wounded in a shooting outside the headquarters of the US National Security Agency in Maryland.
A suspect, apparently uninjured, has been arrested and is being held in custody, according to local reports.
Security officials have not provided details of the incident and it was unclear whether shots had been fired by a suspect or by law enforcement.
Pictures and video of the scene appeared to show a black car with bullet holes in the windscreen outside the facility in Forte Meade.
A White House spokeswoman confirmed that President Donald Trump has been briefed on the incident.
The FBI tweeted to say it was of the incident and was sending personnel to respond. It later added that the situation had been “contained”.
Anne Arundel County police and fire department were assisting.
Earlier local media reports said that as many as three people had been wounded.
The National Security Agency/Central Security Service is one of the U.S. government’s main spy agencies. The secretive agency focuses on using technological tools, including the monitoring of internet traffic, to monitor the government’s adversaries.