Undercover police followed a suspected Iranian terrorist into a café ordering coffee and donuts before 'jumping' on the suspect.
Shocked witnesses told today how a team of six officers dressed casually in jeans and hoodies, sat in a café ordering donuts and drinks as they posed as ordinary customers.
Just moments later, they leapt on a 29-year-old Iranian man suspected of plotting a deadly terrorist attack in Britain.
Shocked bystanders captured the moment on camera that the undercover team swooped outside a Costa coffee shop in the middle of Swindon town centre on Saturday.
The officers were then seen dragging the suspect through the street towards a police van.
One eyewitness told the BBC that six men entered a café the suspect was in and sat opposite him, before ordering coffee and donuts.
When the man left, they followed him out and 'jumped on' him in the street 'just near a Costa coffee', they said.
Today counter terrorism officers are continuing to question the suspect, along with three other Iranian men arrested 'on suspicion of preparation of a terrorist act' in co-ordinated raids on addresses in West London, Rochdale, Swindon, Manchester and Stockport on Saturday.
Undercover police officers swooped on a suspected Iranian terrorist in Swindon after posing as customers in a café and ordering coffees and donuts. Pictured are the officers in action
It was part of a series of busts across England. Pictured are a group of Counter Terrorism Specialist Firearms Officers outside a home in Rochdale during another raid on Saturday
Members of the SAS are suspected to have supported counter terrorism police during the operation to storm the alleged terror cell in Rochdale over the weekend (pictured)
Sources close to the investigation described the alleged plot to target a UK premises as a 'major attack', which could have resulted in an imminent threat to life had it been successful.
Four Iranian men have been arrested on suspicion of preparation of a terrorist act, contrary to section 5 of the Terrorism Act 2006.
A fifth man held in Cheadle Hulme, Manchester, whose nationality is yet to be established, was detained under the Police and Criminal Evidence Act.
During the raid in Cheadle Hulme police arrested a 14-year-old boy and two men after mistaking them for terrorists when they appeared to run away from the scene.
Police said the trio were stopped due to the 'severity of the alleged offences' and to 'ensure public safety', but they were later released after officers realised they were not linked to the alleged plot.
Zakakariya Alexander, 14, told the Manchester Evening News he panicked on seeing officers: 'The car pulled up in front of me and I just saw guns and balaclavas.
'I didn't see their hats and they didn't shout police. I thought it was a kidnapping - I just ran away.'
Children had been playing nearby when police swooped.
One local resident Sarah Cash said she saw the suspect sitting on the floor with his hands cuffed behind his back.
Another local described seeing the 'man lying on the ground with cable ties on his wrists and ankles - and he had police with guns trained on him.'
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Officers are seen detaining one suspect while another officer covers the window of a building
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Police were continuing to search a property connected to a 40-year-old suspect in Rochdale today following the raid on Saturday.
A broken window could be seen at the front of the property, which appears to have been divided into flats.
Neighbours said the house was a HMO with 'at least three or four' people living there.
One neighbour Raman Daniels, 36, said of the raid: 'I heard a massive bang,' he said.
'At first, JetBlack I though it was the kids jumping around on the bed.
'But then my eldest son said it was the police.
'I didn't realise at the time why the house was being raided.
'But now I know it was terror-related it's a bit scary.
'You just don't think that something like this happens on your doorstep.'
He added: 'There were at least three men living there, including the man who's been arrested.
'I don't know their nationalities.
'Sometimes, I'd see people coming and going at night so I thought they might work night shifts.'
About 27 miles north, in Rochdale, counter-terror cops are believed to have been joined by an elite strike force from the Special Air Service (SAS) to carry out a raid.
It's believed the officers in black uniforms are specialists from counter-terrorism police. They are thought to have been supported by members of the SAS
A police officer is pictured at the scene of a property in Rochdale which was raided by counter-terrorism police over the weekend
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It is believed members of the SAS's specialist counter-terror team - dubbed the 'special projects' unit - may have supported armed officers in the raids.
A former British spymaster added that given the alleged threat posed by the radicals - who were reportedly hours away from staging a massacre - it was 'distinctly possible' the British military played a supporting role in the busts.
The Ministry of Defence will never comment about special forces operations.
However, one former SAS operator told MailOnline it was likely a squad from the fearsome 'Who Dares Wins' regiment may have been involved in storming the Rochdale property alongside counter-terror cops.
Soldiers would likely have been armed with explosives to blow open doors, with police supporting the operation, the expert said.
Pictures from the scene show men wearing military helmets and body armour, carrying what are believed to be suppressed C8 rifles - which are used by the SAS.
Other images show a number of officers wearing black and grey tactical kit. It's believed these are highly trained Counter Terrorism Specialist Firearms Officers (CTSFOs).
Locals reportedly heard a series of loud bangs and men shouting before suspects were led out the property by counter-terrorism experts.
'There was a massive explosion and flame. It was officers using explosives to blow open the door,' one local said.
Images showing the aftermath of the security operation also reveal a ground-floor window in the home that was raided had been smashed in.
It's thought this could have been done in order to allow officers to toss in explosive flash-bang grenades before storming the alleged terror den.
Yesterday, residents described how around 30 armed police supported by Special Forces burst into a terraced property in Rochdale on Saturday at around 7pm.
A window in the property in Rochdale that was raided appears to have been smashed. Locals reportedly heard a series of loud explosions before the suspects were detained
On Sunday, residents described how around 30 armed police supported by Special Forces burst into a terraced property in Rochdale on Saturday at around 7pm. Neighbours captured the moment on camera as a 40-year-old Iranian was dragged outside in just his underpants
Neighbours captured the moment on camera as a 40-year-old Iranian was dragged outside in just his underpants.