The shooting incident on Wednesday at the headquarters of the US National Security Agency outside Washington does not appear to be a terror attack, an FBI official said.
"There is no indication that this has a nexus to terrorism," said FBI Special Agent in Charge Gordon Johnson.
Three people were arrested after their vehicle crashed at the entrance to the ultra-secret US spy agency in Fort Meade, Maryland, Johnson said.
One of the three was injured and sent to a hospital, and the other two are in custody. Two other people -- an NSA police official and a bystander -- were also injured and sent to hospital, he said.