A four-story building being demolished collapsed in Philadelphia yesterday, injuring 12 people and trapping two others, the fire commissioner said.

Rescuers were using buckets and their bare hands to move bricks and rubble

Late yesterday rescue crews were trying to extricate the two people who were still trapped, city Fire Commissioner Lloyd Ayers said. The dozen people who were injured were taken to hospitals with minor injuries, he said.

The collapse involved a building that once housed a first-floor sandwich shop.

It sent debris on to a Salvation Army second-hand shop next door. The two were adjacent to an adult bookshop and theatre that had been taken down earlier.

Rescuers were using buckets and their bare hands to move bricks and rubble to search for survivors.

Witnesses said they heard a loud rumbling sound immediately before the collapse.

Veronica Haynes was on the fifth floor of an apartment building across the street.

“I was standing there looking out my window, watching the men at work on the building, and the next thing I know I heard something go kaboom,” she said.

“Then you saw the whole side of the wall fall down... on to the other building.”

Roofers Patrick Glynn and Anthony Soli were working on top of a nearby building when they heard what sounded like two loud bangs or explosions.

They immediately ran down the scaffolding to look for victims, and helped pull out two women and a man.

Glynn said he had been watching workers take down the building next to the Salvation Army shop over the past few weeks, and said he suspected a collapse was inevitable because of the methods the workers were using to tear it down.

Carlton Williams of the city’s Department of Licenses and Inspections said there were no existing violations on the building and the demolition company had proper permits for the work they were doing.

The accident happened at 10.45am local time on the western edge of the central district, between the city’s business area and its main train station.