Five men have been detained on suspicion of explosives and terrorism-related offences after authorities declared a major incident near an airbase in western England.

Bomb disposal specialists are inspecting several vehicles close to RAF Fairford in Gloucestershire, while dozens of nearby homes have been evacuated as a precaution.

Here is what has emerged so far.

Gloucestershire Police said they were alerted at 00:45 BST on Sunday to reports of "three suspicious vehicles" heading in the direction of RAF Fairford.

Officers later arrested five men near Whelford, a village roughly two miles (3.2km) south-east of the base.

Bomb disposal officers were sent to the village to inspect several vehicles, police said. A 400m (1,312ft) exclusion zone has been established around the area.

Images taken from the air appeared to show a remotely operated device moving towards two parked white vans in a wooded location, although police have not confirmed whether such equipment was used.

Counter Terrorism Policing (CTP) is directing the investigation. The operation is understood not to have begun as the result of prior intelligence.

RAF Fairford lies in the Cotswolds, around four miles (6.4km) south of Fairford, a town beside the River Coln.

The airbase has longstanding ties with the US military and has recently been used by American aircraft as a staging point for defensive operations involving Iran.

The US military said it was working alongside British counterparts to follow developments, reduce disruption and protect US personnel, their families and local residents.

Emergency services have maintained a significant presence since the early hours of Sunday. Gloucestershire Police Temporary Chief Constable Maggie Blyth said it would remain in place for the coming days.

At a news conference on Sunday evening, Blyth said the force would continue supporting CTP and coordinating with national agencies.

She said any decision to formally classify the event as a terrorist incident would rest with CTP.

The five men were first held on suspicion of offences under the Explosives Act.

They were subsequently rearrested on suspicion of preparing an act of terrorism.

The men have not been identified and remain in custody. Police have not disclosed where they are being held.

Under the Terrorism Act 2000, suspects may be held without charge for up to 14 days, compared with the usual 24-hour detention limit unless further authorisation is obtained.

When asked whether officers were trying to trace anyone else, Blyth said she believed the situation was "contained".

US President Donald Trump said the men were allegedly planning to cause serious harm, saying authorities had watched them for some time before making the arrests.

An image said to show the detention of five men has been submitted to BBC Your Voice.

It appeared to show men being detained in Whelford, approximately 350m (1,148ft) from runway access at Crash Gate 6A at RAF Fairford.

Although the original source could not be independently established, BBC Verify geolocated the image and found it appeared to be genuine.

BBC Verify has also examined the branding visible on three white vans parked near RAF Fairford.

One verified image showed a red logo on a van carrying the name "Fuel 2You", along with a mobile telephone number.

When the number was called, it directed callers to an automated Lycamobile voicemail message.

No evidence has been found that "Fuel 2You" is an established UK company or genuine operating brand.

However, BBC Verify contacted Fuel2U, a similarly named diesel delivery business. A spokesperson said the vehicles had no connection to the firm.

"For us, it is an extremely unfortunate coincidence," the spokesperson said. "The spelling, number and branding are all different, so it is not an earlier version of our identity."

They said all of the company's vans had been accounted for, adding that any stolen vehicle would still display its own logo, which was not visible on the vans in question.

The firm also said it was recently launched and had never previously traded under the name "Fuel 2You". Its vehicles use green branding rather than red.

A resident who contacted emergency services after seeing the three vans in Whelford said it was only by chance that she noticed them.

Speaking anonymously, she said she returned home to find her driveway and road obstructed, before seeing a "large group of hooded and masked men".

"When they noticed me, they ran ahead of me - some into the field and others towards the neighbouring village of Kempsford. That was when I realised something very unusual was happening," she said.

She said she initially tried to call Ministry of Defence police at RAF Fairford but did not receive an answer. She then called 999 at 01:36 BST and said armed officers filled the village within 10 minutes.

"I believe my call to 999 stopped whatever they were planning."

"I am completely astonished that it was left to a member of the public to spot and report it," she said.

"Somebody clearly failed in their responsibility."

Another local resident described seeing officers detain the suspects.

Jeff, who did not provide his surname, said he heard shouting outside his home but could not tell exactly where it was coming from.

He said he looked through his window and saw people being held by police nearby.

Gloucestershire Police said evacuated residents would not be able to return to their homes on Sunday night.

Cotswold District Council will arrange overnight accommodation for affected people who cannot stay with relatives or friends, according to Deputy Chief Executive David Stanley.

Eighty-five households were evacuated following the incident and directed to a nearby leisure centre for shelter.

Several residents told the BBC they had been woken by officers in the early hours of Sunday and instructed to leave immediately.

"We just had to put some clothes on and go. We had no idea what was happening," said one resident, who gave her name only as Jo.

Another resident, Jason, said: "Everything happened so fast. We packed a few things and came straight here."

A BBC reporter at the leisure centre said several people were still dressed in pyjamas.

Prime Minister Andy Burnham described the event as "deeply concerning" and said the government would take all necessary action to keep the public safe.

He urged people not to speculate while investigators work to establish the full circumstances.

Speaking on Monday, Defence Secretary Wes Streeting thanked members of the public for remaining alert and quickly notifying emergency services.

He said the woman who made the 999 call had done the right thing, but added that she had only seen part of the overall situation.

The defence secretary said it would be inappropriate to speculate about possible Iranian involvement.

Addressing broader threats from Iran, Streeting said: "We know that Iran and its proxies wish to cause us harm."

"In the dangerous and unstable world we now face, spending on defence is a cost worth meeting," he added.

RAF Fairford has served as a forward operating base for the US Air Force for many decades.

The site was used by US Strategic Air Command during the Cold War and again during the first Gulf War in 1991.

USAF B-52 bombers also operated from RAF Fairford during missions targeting Iraq in 2003.

Most recently, it was used on 1 March after former prime minister Sir Keir Starmer approved the use of UK bases, including RAF Fairford, for defensive US action against Iranian capabilities.

Tensions across the Middle East escalated after the US and Israel carried out large-scale strikes on Iran on 28 February.

Iran responded with attacks directed at Israel and US-aligned Gulf states.