ISTANBUL / KARACHI, Pakistan

The death toll from a massive explosion in a factory in Pakistan's industrial hub Faisalabad on Friday jumped to 20, as rescuers pulled out another five bodies from the rubble, an official said.

Deputy Commissioner Faisalabad Nadeem Nasir told reporters that 20 people died, and another 20 people have been injured -- several of them critically -- in the explosion, as the rescue operation is still underway.

​​​​​​​Police said that 17 bodies were pulled out of the rubble, while three succumbed to their wounds at hospital.

Authorities fear a further rise in the death toll.

The dead and injured include children and women, as the massive explosion caused the factory building and several nearby houses to collapse.

Nasir further said that at least four people, including the factory manager, have been taken into custody in connection with the investigation.

According to the initial investigation, he added, the explosion was caused by a gas leak.

Pakistan has had a long history of industrial accidents, mainly because of poor safety standards.