Three people who tried to drive onto the campus of the U.S. National Security Agency near Washington, drawing gunfire from guards, were taken into custody on Wednesday in an incident the FBI said had no link to terrorism.

At least three people, including the driver, were injured.

The motorists, who were not identified, drove a black sport utility vehicle to a gate of the secretive government body in Fort Meade, Maryland, shortly before 7 a.m. EST (1200 GMT). Armed guards fired on the vehicle after it violated NSA security rules, officials said.