Workers can be seen pointing up towards the back of the building site; part of which appears to have caved in slightly. Photo / Jason Oxenham
Up to seven people fell 2.5m. Four were taken to North Shore Hospital with moderate injuries, a St John Ambulance spokeswoman said, and three were treated at the scene.
A police spokeswoman told the Herald a number of people suffered minor injuries, but that no one was trapped.
Carpenters and concrete workers say a building being constructed by Haydn and Rollett was having concrete poured on the second floor when it suddenly caved in.
The building is close to the North Shore District Court.
Workers can be seen pointing up towards the back of the building site; part of which appears to have caved in slightly. Photo / Jason Oxenham
At the site, several workers are standing around an area taped off with orange cones and yellow "caution" tape.