LAHORE, PAKISTAN (BNO NEWS) -- At least thirteen people were killed on early Monday morning when a factory building collapsed in eastern Pakistan, rescue officials said. Dozens more are feared to be trapped under the rubble.

The accident happened at around 8:15 a.m. local time when a suspected gas cylinder exploded at a three-story factory building in Lahore, the provincial capital of Punjab. The powerful explosion devastated the building as more than 60 people were working inside.

As of early Tuesday morning, rescue officials said thirteen bodies had been recovered, including three children. At least 13 others were pulled out alive from underneath the rubble, but it is feared that as many as 30 people could still be trapped. Rescue operations were ongoing overnight.

Pakistan's Rescue 1122 Director General Rizwan Naseer said rescue teams were communicating with at least three survivors who remain trapped under the debris, but he said it could take a long time before the rescue operations are complete. Many of those working at the factory, which was operating illegally and producing veterinary pharmaceuticals, were children.

Pakistan's Construction and Works chief Sabir Khan Sadozai told the Express Tribune that the factory was not operating according to safety codes, adding that such a company is not allowed to operate in residential areas due to health hazards. But the factory has been operating in the area since 1981 and, despite being closed twice by authorities, the company later managed to reopen.

Monday's explosion and collapse also destroyed two adjacent residential houses, but rescue workers were able to rescue the residents without injuries. According to the state-run Associated Press of Pakistan (APP), police are investigating the incident but no arrests were made as of Tuesday morning.

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