Three people, including a police officer, were injured after authorities say a vehicle tried to enter the secure campus of the National Security Agency at Fort Meade on Wednesday morning.

Gunshots were fired during the incident, but officials say they do not believe any of the injuries resulted from gunfire.

At a news conference Wednesday afternoon, Gordon Johnson, special agent in charge of the FBI’s Baltimore field office, said the FBI is still collecting evidence but believes it was an isolated incident.

“I cannot emphasize enough that we believe there is no indication that this has a nexus to terrorism,” Johnson told reporters gathered at a parking lot next to the National Cryptologic Museum.

Johnson said the three injured were the driver of the vehicle, an NSA police officer and a civilian onlooker. He would not give any details about how they were injured or who opened fire.

Two other people who were in the vehicle have been taken into custody and were being questioned, Johnson said. The injuries suffered by the police officer and the onlooker did not appear to be life threatening, he said. He did not have any information about the driver’s injuries.

The incident began when the vehicle tried to enter the spy agency’s campus without authorization around 7 a.m., the NSA said in a statement. The statement said weapons were fired but “preliminary reports do not presently indicate that there are injuries attributable to gunfire.”

The FBI is leading the investigation.