The main gate to Campbell Barracks at Heidelberg, Germany, was closed for two hours Thursday due to a bomb threat that occurred during a force-protection exercise.

The alleged bomb was not part of the simulation, said members of the U.S. Army Europe exercise evaluation team in an Army Garrison Heidelberg news release.

According to the release, the driver — an American civilian — and one passenger drove up to the gate around 1:30 p.m.

When questioned by the military police about a box in the vehicle, the driver responded that it was a bomb.

The man and the passenger were ordered to get out of the vehicle and the German police and fire department came to rope off the area.

During the response, the suspect passed out due to the heat.

He was treated by the MPs and the German Red Cross.

Military dog handlers determined the car did not contain a bomb, and the Explosive Ordnance Disposal team was sent home.

The Army’s Criminal Investigation Command is investigating, officials said.