Paramedics‚ fire-fighters and members of the police’s Search and Rescue Unit descended on the scene.
A concrete slab lay over what appeared to be an articulated truck and a burst pipe sent a stream of water rushing skyward.
Rescuecare spokesman Garrith Jamieson said that several injured construction workers had been treated and stabilised at the scene by medics‚ before they were transported by ambulance to a nearby hospital.
The effort to recover the bodies trapped underneath the rubble has begun.