Five men have been arrested on suspicion of preparing a terrorist act and explosive offences after three "suspicious vehicles" were reported travelling towards an RAF base, police have said.

A major incident was declared and dozens of homes near RAF Fairford in Gloucestershire were evacuated following the report at about 00:45 BST on Sunday.

An Army explosive ordnance disposal team has been examining vehicles near the base, which is used by the United States Air Force (USAF), as counter-terror police lead the investigation.

Residents evacuated from the nearby village of Whelford have been told they will not be able to return home overnight, but officials say they believe the incident is contained.

Aerial pictures showed a remote-controlled robot approaching stationary white vans in a wooded area, though its use has not been confirmed by police.

A 400m cordon has been placed around the area, where a bomb disposal team and hazardous area response team were deployed as part of a major emergency service response.

Prime Minister Andy Burnham was kept updated on the situation on Sunday, which he said would be "deeply concerning for local residents".

Counter Terrorism Policing (CTP) and Gloucestershire Police said the probe was in its early stages, with the five men still in custody as of Sunday evening.

The BBC understands the operation was not intelligence led. The men were initially arrested by Gloucestershire Police and detained on suspicion of committing offences under the Explosives Act, before being further arrested on suspicion of preparation of a terrorist act.

The force's temporary Chief Constable Maggie Blyth said they would continue to assist CTP but would leave any declaration of a "terrorist incident" to them.

Asked whether police were seeking other individuals in connection with the incident, Blyth told a news conference late on Sunday that she believed the matter was "contained".

An image purporting to show the moment five men were arrested was sent to the BBC.

It showed detained men in Whelford, about 350m (1,148ft) from runway access at Crash Gate 6A at RAF Fairford.

The BBC has been unable to verify the original source, but BBC Verify has geolocated the image and confirmed it appeared to be authentic.

The base shares a long history with the American military, and has recently been used by US warplanes as a staging post for defensive strikes on Iran.

US President Donald Trump said those arrested had been "looking to do big damage", adding: "We had them under view for a long time, and we got them."

UK Defence Secretary Wes Streeting said he had been in contact with his US counterpart, Pete Hegseth.

A USAF spokesperson said its personnel remained vigilant but did not discuss specific force protection methods.

The US Department of Defense meanwhile raised the threat level at RAF Lakenheath in Suffolk - which hosts the USAF's 48th Fighter Wing - to its second-highest category.

A local resident told the BBC she alerted the police to suspicious activity near the base early on Sunday.

The woman, who did not want to be named, said she initially called the Ministry of Defence (MoD) police but nobody answered, and then called 999. She said she had seen three parked vans and a group of men wearing masks.

The MoD declined to comment.

Several residents said they had been led from their homes in the early hours and evacuated to a leisure centre.

Julian Tudsbury said he was woken up at 07:00 by police banging on his door in Whelford, where 85 households were advised to evacuate.

"There were several police, three police cars in the drive, and they said you need to evacuate, there's been a major incident, said he couldn't elaborate," he said.

He said another local had seen three vehicles making their way to the base and called the police "straight away".

Another resident, who gave his name only as Jeff, said he heard shouting outside at 02:00.

"[I] looked out the window and saw men were being held by police outside the house. They were armed, it was surreal.

Gloucestershire Police said displaced residents had been told they would not be able to return to their homes on Sunday night.

Overnight accommodation would be found by Costwold District Council for those affected who were unable to stay with family and friends, according to deputy chief executive David Stanley.