The teenage suspect allegedly behind the Parsons Green terror attack "didn't see" his arrest coming as armed police swooped in on him as he tried to flee the UK.

The 18-year-old seemed shocked and “froze” as officers arrested him at the Dover port ticket office on Saturday (September 16) morning.

According to The Mirror, holidaymakers were sipping coffee and eating breakfast when seven officers, believed to be acting on a tip-off from port staff, caught the suspect and took him away in handcuffs.

The witness said: “He didn’t see it coming. As the officers arrived behind him he froze and appeared stunned.”

Heightened security saw gun cops on the streets all over Britain following the District Line bomb attack at Parsons Green Tube station, on Friday (September 15) morning.

The suspect had been trying to leave Britain as a foot passenger at 7.50am – almost exactly 24 hours after the blast, which injured 30 people.

Police in Dover said potentially vital evidence had been found at the port which had been seized during the arrest.

Officers said “a number of items” could prove vital in helping detectives probing the attack.

Dover Port, where detectives investigating the Parsons Green bombing have arrested an 18-year-old man on suspicion of a terror offence

A port worker told the Sunday Mirror: “He was surrounded by about seven police officers after he came in to buy a ticket.

“It was all done very quickly and quietly. There was no sign of a struggle. It was difficult to see him or what he looked like because they moved towards him so fast.”

Ghiocal Duculescu, from Romania, was sitting in the port terminal at the time of the arrest.

He said: “There was no fuss or drama. He must have walked right past us and then been taken away quickly into a back room.”

It is understood the suspect had travelled from London Victoria by train then walked 30 minutes from the rail station to the port. Police in black boiler suits evacuated the terminal three hours later.

They then conducted a forensic search of the area and bins outside the port. Further police probes were being carried out at the town’s Dover Priory train station.

Three officers were seen taking a sniffer dog into toilets and unlocked rooms just after 6pm.

They were also spotted checking the insides of parked cars with torches. An officer told one concerned member of the public they were carrying out extended searches “just to be on the safe side".

The suspect was quizzed by anti-terror police at the port before being driven away in a convoy of cars with flashing blue lights at 12.30pm, and is being held at a secure South London police station.

Kevin Rodgers, 58, a retired Kent Police officer, was up a ladder ­decorating the outside of his house above the entrance to the port at the time of the drama.

He said: “We saw three unmarked cars with their blue lights flashing drive out of the port at speed towards the A2.”

Since the first arrest, police carried out a huge armed raid at a property in Sunbury on Saturday (September 16) afternoon.

The following morning, a second arrest was made at an address in Hounslow.

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