Most of the deaths were caused by suffocation as people caught in the basement were unable to escape when it filled with smoke, said the top firefighter in Karachi, Ehtisham-ud-Din.
There were no fire exits, and the doors leading out of the basement were locked, he said. It's unclear what caused the fire.
Workers on higher floors of the five-story building struggled to make it out of windows that were covered with metal bars.
Many were injured when they jumped from the building, including a 27-year-old pregnant woman who was injured in the fall.
