KARACHI, Pakistan >> Four firefighters died and nearly a dozen others were injured after a massive fire broke out in a garment factory in the southern Pakistan port city of Karachi, rescue officials and police said Thursday.

The cause of the blaze, which ripped through the factory Wednesday night and eventually caused it to collapse, was not immediately known, police said. Earlier, heavy gray smoke suddenly rose from the factory. Firefighters had almost extinguished the blaze when the collapse occurred.

Rescuers have retrieved the bodies of the firefighters from the rubble of the factory.

Several firefighting vehicles were dispatched to the scene in an industrial area of the city, where many factories are located, officials said. Officers were also assessing the impact of the fire at an adjacent building.

Pakistani Prime Minister Shahbaz Sharif expressed sorrow over the deaths of firefighters, describing them as “martyrs” who died while trying to save the lives of others. In a statement, he conveyed his condolences to the families of the victims.

Sharif ordered authorities to prepare a strategy to avoid such incidents in future.

Karachi is the capital of southern Sindh province, where such incidents are common. In August 2021, at least 10 people were killed in a massive fire at a chemical factory in Karachi. In the deadliest such incident, 260 people were killed in 2012 after being trapped inside a garment factory when a fire broke out.