The circumstances surrounding the apparent effort to breach a gate at the National Security Agency on Fort Meade remained cloudy Wednesday afternoon. But the FBI said it wasn’t linked to terrorism.

According to the FBI, an SUV with three males was stopped as it tried to enter the NSA campus through the Canine Gate off Maryland Route 32 around 7 a.m. Wednesday.

There were reports of gunshots being fired and of three people—the driver of the SUV, an NSA gate guard and a bystander--being injured and taken to local hospitals. But an NSA statement said that preliminary reports do not indicate their injuries were attributable to the gunfire.

Gordon Johnson, special agent in charge of the FBI’s Baltimore Field office, said in an afternoon news conference the FBI was still collecting evidence.

“Again this is part of our investigation to determine exactly what happened here,” he said. “This vehicle did come onto the NSA compound unauthorized.”

Johnson said the others in the car were in custody and were being questioned by FBI agents, but they haven’t determined a motive for the incident.