A residential building has collapsed in Mumbai (Bombay), killing 11 people and injuring more than 20.

At least 20 others are believed to be trapped in the debris while nearly 50 people have been rescued by the emergency services.

One report said the four-storey building was more than 100 years old and had been in a poor condition.

Two adjacent buildings were also evacuated as rescue workers continued to search for survivors.

The run-down building was home to at least 16 families, city officials said.

Most residents were asleep when the structure collapsed shortly after 0100 (1930 GMT).

"According to reports, the entire building collapsed in one go late at night when all the people were asleep," Mumbai's chief fire officer, AD Jhandwal, told the AFP news agency.

Abdul Sheikh, who lives opposite the collapsed building, told the Hindustan Times: "We were fast asleep when we heard a loud noise. Initially, we suspected it to be a bomb blast but when we came out we saw the collapsed building.

"The local people started rescue operations immediately. But since we didn't have critical equipment like excavators and cranes, we couldn't move the huge boulders and pull out many people."

Desperate scramble

Rescue workers are now at the scene. One police officer told Reuters: "There is a very large crowd now and the streets are very narrow, so rescue efforts have slowed down a bit."

Correspondents say it is not uncommon for poorly maintained buildings to collapse during the monsoon rains in Mumbai.

A police officer told Reuters the local government had declared the building unfit.

"I believe the Mumbai Corporation had declared it unsafe and served them notice," he said.

The chief minister of Maharashtra, Vilasrao Deshmukh, said an inquiry into the cause of the collapse had been ordered.

He said his government regretted the incident and help would be given to the families of the victims.

According to one estimate, there are some 19,000 high-rise buildings in Mumbai that are "old and dilapidated".

Last month, more than 1,000 people were killed in record-breaking downpours in the city and its state of Maharashtra.

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