Two dead and dozens trapped in Mumbai building collapse

Mumbai has been hit by days of heavy rains. Photo / AP

A building has collapsed in Mumbai's commercial hub with two people confirmed dead and more than 30 feared trapped.

The collapse today came after two days of torrential monsoon rain in India.

One body had been found and a second victim was declared dead at hospital, while eight survivors have been pulled from the rubble, a police official said as rescue operations continue.

Nine families were living in the building, which is located in Mumbai's Dongri neighbourhood - an area of narrow streets and closely packed buildings, some nearly a century old, a police said.

Television images show people on top of the debris, looking for those trapped as rescue personnel reached the spot.

"Rescue operations are already underway. We have sent 12 fire brigade vehicles to the spot. Ambulances are also ready to take the victims to the hospital," the fire control room official said.

Police suspected the heavy rains that lashed the could have weakened the building.

Last month, 17 people were killed when a four-storey building collapsed in an eastern suburb of Mumbai.

Torrential monsoon rains are also lashing Pakistan's port city of Karachi.

TV footage showed streets were submerged already after the heavy rains began today.

Pakistan's meteorological department says rains will continue for three days in various parts of Sindh province, where authorities closed schools as a precaution. Windstorms and rains are also expected in the southwestern Baluchistan and eastern Punjab provinces.

The meteorological department says rains are also expected in the capital, Islamabad, and in Pakistan's portion of Kashmir.

Rains regularly trigger floods in South Asian nations during the monsoon season, which runs from June through September.

-AAP, AP