MUMBAI: At least 29 people — mostly labourers and their families — were crushed to death on the outskirts of Mumbai after a building collapsed while under construction, police said on Friday.

As rescuers combed the rubble for survivors, two toddlers were pulled out alive to cries of “God is great” and cheers and clapping, an AFP photographer at the scene said.

The seven-storey building collapsed on Thursday evening, creating a mangled heap of steel and concrete of about 8 metres (26 feet) high that rescuers and local residents struggled to cut through.

Rescue efforts continued through the night, with diggers and steel cutters employed to reach victims who were carried away on makeshift stretchers. Limbs protruded from the wreckage in a grisly scene.

“Twenty-nine people have lost their lives so far. We have rescued 60 people, some of whom are injured,” said K.P. Raghuvanshi, the police commissioner of Thane district, about 35 kilometres from the Indian commercial capital.

Most of the victims were migrant labourers who come to Mumbai to find work on building sites, earning as little as a few hundred rupees (about $6) a day.

They often bring their wives and children, who live on-site.

The local civil administration said it was probing the incident and would check other new structures built recently in the vicinity, a middle-class commuter area with modern-style residential blocks.

“The building (that has collapsed) was an unauthorised construction. We are going to investigate thoroughly into this and prepare a report,” Sandeep Malwi, spokesman for the Thane municipal corporation, told AFP.

The Hindustan Times daily said the builders may have ignored building regulations.

“Seven floors were built in merely three to four months. It was bound to collapse due to the inferior construction material used by the builders,” the paper quoted the local head of the disaster management cell as saying.

Building collapses are a common occurrence in India, where a booming economy has led to a mushrooming of multi-storey structures which are often unauthorised and flout safety laws.

In February, the collapse of a flyover bridge being built at Mumbai's main airport killed three people and injured another seven.

In one of the worst such accidents of recent years, 69 people died and more than 80 were injured in November 2010 in New Delhi where a residential building under construction collapsed, trapping families in the lower floors.