Firefighters were called to Mansergh Barracks on Monday to put out a blaze that started in one of the buildings.
The fire, which was in a groundfloor room belonging to 26 Regiment RA, took two-and-a-half hours to get under control and involved 45 firefighters.
The alarm was sounded at 11.40am and 10 firefighters were equipped with breathing apparatus to avoid breathing in toxic smoke while fighting the flames.
Gütersloh fireman, Thomas Köhler, said: “When we arrived, flames were shooting out of the window.”
At 2pm the fire was extinguished and the firefighters left the barracks.
An MoD Spokesperson said: “The German emergency services were called to attend to a fire in Mansergh Barracks, Gütersloh on June 12. An evacuation of the building was carried out in accordance with standard practices and there were no reported injuries.
“An investigation into the cause of the fire is ongoing and it would therefore be inappropriate to comment further or speculate on how the fire may have started until the formal investigation is concluded.”