British police declared a “major incident” on Sunday near a major Royal Air Force base used by the United States for strikes against Iran, with five men arrested on suspicion of preparing a terrorist act that appeared to involve three vans.

RAF Fairford, which the United Kingdom authorized the U.S. to use for defensive strikes against Iran, is an important base for the U.S., as it hosts U.S. heavy bombers, which were used during the intensive combat phase of the war to hit entrenched, high-priority targets. The arrests occurred near the village of Whelford, roughly 2 miles from the base, and Gloucestershire police evacuated local residents to a nearby leisure center.