Early on Wednesday, a driver collided a vehicle into the gate of the FBI’s office in Pittsburgh, then nonchalantly walked away, prompting the agency to handle the incident as “an act of terror.”

The vehicle, which was adorned with offensive messages, crashed into the rear entrance of the building located on the city’s south side at approximately 2:40 a.m. The driver emerged from the car, tossed an American flag over the fence, and yelled unintelligibly.

Authorities said they were hunting Donald Henson, a former military man with a history of mental health issues.

“We consider this an act of terror directed at the FBI,” stated Christopher Giordano, the Assistant Special Agent In Charge at FBI Pittsburgh, as reported by CBS News.

“This was a targeted attack on this building.”

The car appeared to have some profanity-laced messages on one of its side windows, which Giordano said is being investigated, according to WTAE, which did not elaborate on what they said.

Nobody was hurt during the incident, the FBI said.

 A bomb squad was called to the scene and the white Toyota was seen being searched by authorities outside of the gate.

A manhunt is now underway for Hanson, of Penn Hills, who does not appear to be armed but has a history of mental health issues, the FBI said.

Nakeisha Brown, who works nearby, told WTAE she heard screeching tires and saw the suspect yelling before he left the scene.

“He got out and went around the passenger side and pulled something out of the passenger side,” she said. “I thought it was a gun but it happened to be a flag and he just set it on that fence and started yelling out some words and just took off.”

“He just walked away like nothing happened,” said another nearby worker, Idez Columbie.