British counterterrorism police said Sunday that five men arrested near Royal Air Force (RAF) Fairford, an air base used by U.S. bombers in the Iran war, are being held on suspicion of preparing a terrorist act.
Police received a call at about 12:45 a.m. Sunday about "three suspicious vehicles traveling towards RAF Fairford," Gloucestershire Assistant Chief Constable Richard Ocone said.
Armed officers arrested the men, and about 85 households were evacuated while army bomb disposal experts examined the vehicles.
RAF Fairford hosts the U.S. Air Force's 501st Combat Support Wing and has been used for U.S. strikes on Iran. Police have not said whether the arrests are linked to the base.
"Counter Terrorism Policing can now confirm they are leading an investigation into an incident which took place overnight near RAF Fairford in Gloucestershire," London's Metropolitan Police said.
The men were first arrested on suspicion of offenses under the Explosives Act and were then further arrested on suspicion of preparing a terrorist act under Section 5 of the Terrorism Act. They remain in custody for questioning.
Deputy Assistant Commissioner Vicki Evans said investigators were in the "early stages of an investigation, and five men remain in custody."
"We continue to work with Gloucestershire Police to keep the community safe as we work to gather evidence from the scene," she said.
The operation was not intelligence-led, meaning investigators had no advance knowledge of any plot, the PA news agency reported.
"A 400m cordon was put in place around the vehicles, while they were examined by the Army's Explosive Ordnance Disposal Unit," Ocone said, describing the measure as a precaution.
Residents of Whelford, a village next to the base, were moved to a nearby leisure center. Aerial footage from Sky News appeared to show a bomb disposal robot moving between three white vans. Police later extended the cordon as far as the nearby village of Kempsford, and army vehicles blocked entrances to the base.
Julian Tudsbery, a Whelford resident of 30 years, said police arrived and told residents to leave. "They said you need to evacuate; there's been a major incident," he said, adding he couldn't elaborate.
Another resident, Jason, told reporters, "The police response was very rapid. They just need to clear the area now. Just hoping to go home."
Defense Secretary Wes Streeting thanked emergency teams.
"We can be reassured that this is being dealt with and it is exactly why our emergency response teams and Armed Forces are on standby 24/7," he said.
Prime Minister Andy Burnham is receiving updates, his office said.
A government spokesperson said, "It would be inappropriate to comment further whilst investigations are ongoing."
A U.S. Air Force spokesperson said, "No U.S. Air Force personnel are involved in the incident. We remain in close coordination with our UK partners to help ensure the safety and security of both our military and local communities."
South Cotswolds lawmaker Roz Savage called the situation "worrying" but said police told her it is believed to be contained.
RAF Lakenheath in Suffolk confirmed to PA that it is at FPCON Charlie, the U.S. Defense Department's second-highest threat level, amid reports that RAF Fairford has been raised to the highest level, Delta.
In July, Iran's Revolutionary Guard warned Britain over U.S. bombers flying from Fairford, saying "any base used for aggression against Iranian territory is a legitimate target for us." No link between the arrests and Iran has been established.
The arrests come amid heightened concern in Britain over hostile states, including Russia and Iran, using proxies to commit crimes on British soil.
Police said work is ongoing to establish the full nature of the incident near RAF Fairford.