Emergency services are dealing with a fire at RAF Fairford.
Gloucestershire Fire and Rescue Service said crews were called to a blaze in a commercial building in the Fairford area during the early hours of Sunday.
People living nearby have been advised to keep their windows and doors closed due to smoke.
The base, near the Wiltshire border, is currently used by the United States Air Force.
Images shared on social media appear to show the fire affecting a unit on the site.
The cause of the fire has not yet been confirmed, and emergency services remain at the scene.