Karachi, April 13 : Four firefighters were killed while trying to contain a massive blaze at a factory in Karachi, rescue teams said on Thursday. The bodies were recovered in the morning, Salman Qureshi, a firefighter from Saylani Welfare Trust, told Xinhua news agency. The fire broke out in the multi-storey building of a bedsheet factory on Wednesday morning and a dozen fire engines worked to douse it. "The firefighters were working at the incident site when part of the factory collapsed trapping several people under the debris," Qureshi said. Thirteen injured people, including 11 firefighters, were also rescued, he said. Talking to media, Karachi's Central District Deputy Commissioner Taha Saleem, confirmed there are no more trapped persons under the rubbles, and the area has been cleared by rescue teams. He added that the fire was contained early Thursday morning, and a cooling operation was underway. He said that fire erupted in the building due to a short circuit and it got worse because the firefighters could not take big engines to the site due to congested streets. The officer said that the building's structure weakened due to the big fire and the water used to douse it, leading to its collapse during the process. /IANS