Lahore, Pakistan (BBN)-A major rescue operation is under way to save dozens of people thought to be trapped under rubble after a factory collapsed in Lahore, Pakistan.
At least 20 people died when the plastic bag factory, which was under construction, collapsed on Wednesday.
Officials say the priority is to get to parts of the debris where voices and cries for help can still be heard.
The cause of the collapse is still unknown. Building safety levels are often below standard in Pakistan.
There are reports that the earthquake which hit Pakistan two weeks ago, or faulty construction work, may have contributed to the collapse.
Two floors of the factory, in the Sundar Industrial Estate on the outskirts of the city, were operational, while a third was being built.
One of the trapped workers, Liaqat Ali, was able to call a television station from his mobile phone.
“We were working on the first floor when the roof collapsed,” he said.
“Now, I can hear the rumble of heavy machines which gives me hope that I will come out alive.”

Cranes and bulldozers are being used and the army is assisting in the rescue efforts.
About 200 labourers are thought to have been in the building at the time of the incident, according to Jam Sajjad Hussain, a spokesman for the rescue services.
Other estimates in the Pakistani media have put the figure closer to 150 people.
Mr Hussain told the BBC that 98 people had been pulled out alive and many were then taken to hospital.
He said it was difficult to know exactly how many people were still trapped because the owner and administrative employees were among those inside the building.

The army has said that it is deploying a team of engineers and experts to take part in the rescue.
In September last year at least 24 people were killed in Lahore when the roof of a mosque collapsed.
At least 17 people – including children – were killed in a factory collapse following a gas explosion in a residential area of the city in February 2012.