Another 23 persons have so far been rescued, many of them injured seriously, and rescue work is continuing as some people are still trapped under the debris.

Chief Minister Devendra Fadnavis on Wednesday announced a compensation of Rs five lakh each to the kin of the deceased and Rs 50,000 to all the injured and the government will foot all their medical expenses.

The Chief Minister also convened a high-level meeting of all concerned departments to discuss the building crash and pin responsibility.

On Tuesday, Fadnavis and the Maharashtra Housing and Area Development Authority (MHADA) had announced separate probes into the disaster.

Around 11.30 a.m. on Tuesday, an illegal rear portion of the 80-year-old Kesarbai Building suddenly crashed, burying at least 15 families who were living in the ground-plus-four storied structure.

Among those who have been killed include the building's caretaker Abdul Sattar Shaikh and his daughter-in-law Sabiya Nissar Shaikh besides three minors.

Prime Minister Narendra Modi had expressed grief over the crash in a tweet. "Collapse of a building in Mumbai's Dongri is anguishing. My condolences to the families of those who lost their lives. I hope the injured recover soon. Maharashtra government, NDRF and local authorities are working on rescue operations and assisting those in need."

Kesarbai Building is located in one of the oldest and most congested areas of south Mumbai, and rescue operations were hit with the narrow lanes, huge crowds of onlookers, VVIP movements and the media out in large numbers to cover the tragedy.

JCBs and heavy earth moving equipment could not reach the crash site, ambulances and rescue vehicles had to be parked more than 50 metres on bigger roads, making it one of the most challenging operations for the NDRF and other teams.

However, the local residents helped out by forming human chains to facilitate the relief work, removing the debris in bedsheets, curtains or old saris as time ticked away for those still under the debris.

The Kesarbai Building crash has become the second biggest disaster of the monsoon season this year. On July 2, the compound wall of a BrihanMumbai Municipal Corporation (BMC) reservoir in Malad east crashed following torrential rain that night, killing 30 so far and injuring around 100.