A more than a century-old five-storey residential building collapsed on Thursday in the congested Bhendi Bazar area of south Mumbai, killing at least 19 people and wounding 12 others, officials said.

They were declared dead at the state-run J J hospital, where they were taken after being pulled out of the debris, as rescue teams with heavy machinery continued to look for survivors of the crash, a senior police official said.

About 30 others are still feared trapped under the mounds of concrete and twisted iron rods.

The process of identifying the bodies is on. At least 12 people injured in the incident were carried out on stretchers and rushed to the J J Hospital in ambulances that faced difficulty in navigating the narrow streets due to the crowd gathered around the place.

The official also said five fire brigade personnel and an NDRF jawan also sustained injuries during the rescue operations. They have also been shifted to the J J hospital.

Fire brigade officials said some nine families lived in the dilapidated Husaini Building.

The building also housed a play school but children had not arrived yet when the tragedy occurred.

The building, mostly housing lower-middle class families, was located in the Muslim-dominated Pakmodia Street close to the J J Hospital.

Fire brigade and NDRF personnel carry out the search and rescue operation following the collapse of building at Pakmodiya Street in south Mumbai on Thursday. (Photo: PTI)

What now remained of the 117-year-old structure was a large mound of concrete rubble and steel rods encircled by other houses including what appeared to be a tall building.

Rescue workers in hard hats clambered up the mound and banged large concrete slabs with hammers to reach underneath and pull out survivors and bodies. Cranes and bulldozers were also deployed to scoop up the debris. Residents helped with bare hands.

Maharashtra Chief Minister Devendra Fadnavis visited the spot and announced a solatium of Rs five lakh each for the next of kin of the deceased. He also said that the entire medical expenses of those injured will be borne by the state government.

"The exact number of trapped people cannot be known immediately," deputy commissioner of police (Zone 1) Manoj Sharma said.

"Our priority is to pull out at the earliest those trapped under the rubble of the dilapidated building," said state Industries Minister Subhash Desai, who is also the guardian minister for Mumbai.

"Once the rescue work gets over, the government will conduct a probe to ascertain the factors behind the building collapse. Strict action will be taken against those found guilty," he told reporters.

Revenue Minister Chandrakant Patil and a host of local politicians and corporators also visited the collapse site.

The disaster management cell of the Municipal Corporation of Greater Mumbai (MCGM) received a call about the collapse at 8.40 am.

Fire brigade and NDRF personnel carry out the search and rescue operation following the collapse of building at Pakmodiya Street in south Mumbai on Thursday. (Photo: PTI)

"We immediately rushed fire brigade personnel to the site to rescue the trapped people," a senior MCGM official said.

The rescue operation is being carried out by the NDRF team with the help of fire brigade personnel.

The incident occurred two days after the city was pummelled by torrential rains, which may have caused damage to the building.

Some residents claimed that about 40 people belonging to nine families lived in cramped rooms in the structure, which was declared "unsafe" by the Maharashtra Housing and Area Development Authority (MHADA).

The Saifee Burhani Upliftment Trust (SBUT), which was to have undertaken redevelopment of the 117-year-old structure, said the building housed a total of 13 tenants -- 12 residential and one commercial. "Of them, the trust had already shifted seven families in 2013-14," it said in a statement.

"MHADA notices dated March 28 and May 20, 2011, declaring the building dilapidated, were issued along with an offer of transit accommodation to the remaining tenants and occupants," it said.

This is the second major building collapse in the city in just over a month, after the crash of a residential complex in suburban Ghatkopar on July 25, which left 17 people dead.