MUMBAI - A five-storey apartment block collapsed on Friday in the Indian financial centre of Mumbai, killing at least thirteen people.

Rescuers worked into the night to pull out survivors and casualties from the concrete rubble. City authorities said 46 people were rescued by evening. It was not clear how many more were still in the rubble.

Employees of the Municipal Corporation of Greater Mumbai, also known as the BMC, were housed in the building.

A neighbour in the next block said she heard a loud cracking sound as the building caved in.

"As dust settled, I realised the BMC building was gone," the neighbour, Catherine James, told Reuters.

Rescue workers used six cranes to remove debris. The building was believed to have been about 35-years-old and home to about 20 families.

"Five members from my family were trapped inside. So far, two have been rescued. I am praying to God others will also come out alive," said Preeti Pawar, who was standing among crowds of relatives and onlookers outside the collapsed block.

The cause of the collapse was not known.

Mumbai mayor Sunil Prabhu said the block was not on an official list of dilapidated buildings.

In April, a building collapse killed 72 people in Thane, just outside Mumbai. Officials later said the structure had been built using poor materials and did not have proper approvals.

A shortage of cheap homes has led to a rise in illegal construction by developers who use substandard materials and shoddy methods and then offer cheap rents to low-paid workers.

A rise in property prices in densely populated Mumbai over the past five years has put affordable housing out of reach of tens of thousands of people, many of them migrants who move to the city for work.

"Again and again, the same kind of tragedies are striking but the government is not learning anything," said Vinod Tawde, a politician from the main opposition Bharatiya Janata Party.

"The government should evacuate all people staying in dangerous buildings."

Onlookers cheered and clapped as emergency workers rescued residents. Others climbed onto walls to get a better look at the collapsed block.