“We turned to look and the building was collapsing. It didn’t look planned, as there was lots of scaffolding still up and there were people in the building next door rushing to the windows to check what happened.
“I saw half the building collapsing then there was like this extreme dust cloud.
“We moved as soon as we saw the dust cloud coming towards us.”
GMFRS added, crews were called to the scene at about 14:50 GMT.
Steve Wheeler, who was in the building next door, said: “I heard a loud bang. We were all looking at each other wondering what’s that?
“We didn’t think much of it. It sounded like something had landed on the building.”