At least 11 people were killed and two others were injured on Tuesday after gas cylinders exploded at a perfume factory in Shahdara area of Lahore, setting the entire building ablaze, confirmed officials.

One of the injured, identified as 30-year-old Zahid, was shifted to Mayo hospital in critical condition.

The fire also caused the roof of the building to collapse, trapping other residents of the building beneath the debris as well as damaging the structure located adjacent to it.

Residents of the area said the factory was considered to be a textile manufacturing unit. "We only got to know about the presence of perfume and other chemicals after the fire broke out," one of the residents said.

A rescue operation is under way to rescue the remaining people trapped under the debris. According to residents, at least 15 workers were inside the factory when the fire broke out.

According to hospital sources, the deceased have been identified as 37-year-old Jameel, 65-year-old Zahid, his wife Rashida bibi, six-year-old Areeba nine-year-old Moosa, 45-year-old factory owner Abid, and Naveed.

Rescue 1122 official Rana Izhar said the fire had been brought under control, adding that the deaths were primarily caused by the roof collapse.

Correction: An earlier version of the story had erroneously stated that 12 people were killed in the incident. The error is regretted.