A person working inside a building as it partially collapsed said it felt "like a bomb had gone off".
The Metropolitan Police, London Ambulance Service and London Fire Brigade crews raced to High Street, Stoke Newington, after brickwork tumbled from a building at around 9.30am on Friday.
Workers were evacuated and A and B Glassworks was one of two businesses affected.
A spokesperson for the business said: "The first thing we heard was a shout which was from the builders.
"The next thing we saw was a lot of dust and then within less than a second, huge amounts of rubble started falling.
"I was head of security at the Old Bailey for ten years and I saw a lot of stuff there.
"But [the building collapse] was the scariest thing I've ever seen in my life. It was like a bomb had gone off."
There were no injuries but there continues to be significant disruption in the area and Stoke Newington High Street is still closed between Tyssen Road and Brooke Road.
Hackney Council contractors are constructing a supporting structure in an effort to stabilise the existing scaffold and the building.
The council said it expects the road to remain closed until at least Sunday, February 5.
The A and B Glassworks spokesperson added that the business can no longer operate while supplies are still in the shop.
He said: "The tools are in the shop, the glass is all in the shop and I can't get to it."
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