An explosion of gas cylinders in the basement of a building in the eastern Pakistani city of Lahore has killed at least 24 people, police say.

Many others were injured in the blast, which damaged nearby houses, and rescuers are still searching for people who may be trapped under the rubble.

It is not clear what set off the explosions, though police say sabotage has been ruled out.

The building housed a small ice-cream factory as well as residential flats.

The blast occurred at about 0330 (2230 GMT) when many residents were asleep.

Rescue workers used cranes and bulldozers to remove the rubble.

Dazed survivors were pulled out from underneath huge concrete slabs.

"I heard a deafening bang, then it seemed like the world fell on me and then I passed out," one survivor, Mohammed Mushtaq, told the AFP news agency.

"The next thing I knew I was being pulled out of the rubble by rescuers several hours later."

'Toll could rise'

A spokesman for a local health service provider, Edhi Foundation, told the BBC that the number of casualties could rise.

One report says four women and two children were among the dead.

"The blast was so powerful that it broke window panes of nearby houses," a police official, Zubair Nawaz Chatha, was quoted as saying by AFP.

The injured have been moved to a nearby hospital, the police say.

The BBC's Shahid Malik in Lahore says dozens of people have been killed in incidents involving use of residential premises for commercial purposes in the past five years.

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