UK police arrest several men at an RAF base on suspicion of offences under Britain's Explosives Act, police say.
Since the start of the Iranian war, the US military has used the base to carry out strikes on Iranian missile sites.
An incident was declared with homes evacuated and residents moved to a nearby leisure centre.
Several men have been arrested on suspicion of explosives offences after a security scare at a British air base used by the US Air Force in south-west England.
An incident was declared and homes were evacuated in a village near an RAF Fairford, with residents moved to a nearby leisure centre on Sunday.
It comes after the British government gave authorisation to the US to use RAF Fairford to carry out strikes on Iranian missile sites that are attacking ships in the Strait of Hormuz.
An eyewitness said armed police were blocking access to the main gate of the base.
About 30 emergency vehicles, including police cars, ambulances and fire engines, were stationed in the village of Fairford.
"A number of properties are currently being evacuated following the declaration of a major incident," Gloucestershire police said in a statement.
Police said the men were taken into custody on Sunday morning.
The base has been used to deploy US bombers since the conflict in Iran began on February 28.
On Saturday, US President Donald Trump rejected an Iranian plan to reopen the Strait of Hormuz within seven days, while threatening the possibility of further bombing.