FORT MEADE, Md. — Three men were in custody Wednesday after they tried to drive onto the National Security Agency’s campus at Fort Meade, in Maryland. But officials said the episode did not appear to be linked to terrorism, and that there was no ongoing safety or security threat.

The men tried to drive through the Canine Road gate shortly before 7 a.m. without authorization, said Gordon Johnson, the special agent in charge of the F.B.I. Baltimore division. Weapons were fired in the course of the episode, but preliminary reports did not suggest that anyone had been shot, and the car crashed.

The driver was injured in the crash and was taken to an area hospital, while the other two men were being interviewed by the F.B.I. A police officer and onlooker also were injured, officials said, but the injuries were not serious.

Mr. Johnson and Tommy Groves, an N.S.A. spokesman, said that terrorism was ruled out as a motive during preliminary investigations. They declined to rule out any other potential cause — including whether the driver entered the campus by mistake. The military’s Cyber Command is also located at the base.

Mr. Johnson did not say who fired the shots — whether the occupants of the car or security personnel — as the F.B.I. continued its investigation. He said the N.S.A. police “responded accordingly” to the car’s unauthorized attempt to enter the campus.

The White House said that the president had been briefed on the shooting.

The police force at Fort Meade remained on high alert for people trying to forcibly enter. In 2015, two men were shot, one fatally, when they drove a car onto the campus.