Witnesses have spoken of their terror at the sight of heavily armed police swooping on a van in Wanstead High Street this morning.

Officers with guns surrounded the white vehicle at around 9am and arrested its driver as part of an armed robbery investigation.

Passers-by said plain clothes police jumped from an unmarked car and smashed the van's windows, pulling the man out.

Ricardo Berenger, 42, witnessed the drama unfold.

He said: "I was waiting outside the [NatWest] bank waiting for it to open when suddenly all these people appeared from nowhere and surrounded the van.

"It was very, very scary. I heard two, three, maybe four bangs and there was white smoke. People were running for cover.

"The police were in plain clothes but some of them put police hats on quite quickly to show the public who they were - but at first people weren't sure."

Other witnesses also reported hearing bangs but police have denied any shots were fired. 

A 47-year-old businessman, who did not want to be named, was close to the van when it was pulled over in the High Street close to Wanstead Pharmacy.

He said: "There was a black car driving very slowly down the High Street and people were sounding their horns in frustration.

"I was standing on the pavement close by and then out of nowhere all these police jumped out, some from the black car and I also saw an officer appear on a motorbike. I counted at least 15.

"They surrounded the van and smashed its windows, and I heard these bangs. There were puffs of white smoke. I thought they might be blanks but it was hard to tell.

"People were terrified. There was a woman with a buggy walking by and we ran for cover together in a dry cleaner's.

"I saw the police take the man away but I didn't see a gun. But the police all had guns. 

"When the bangs started of course everyone was worried there might be return fire, there was a bit of panic."

Another witness, aged 33, saw police take away their suspect.

He said: "He was a white guy aged maybe in his 30s or 40s, but it was hard to tell because he had his face down.

"He was put in the back of a police meat wagon and driven off. I didn't see anyone else arrested."

Part of the High Street remains closed.

A Met spokesman said: "This was a Flying Squad operation in relation to an armed robbery suspect".

The Guardian is awaiting further details from police.