A boiler exploded at a towel factory in the southern Pakistan port city of Karachi on Tuesday, killing seven workers and injuring 28 others, police said.
Three people were killed at the scene when the steam-producing boiler exploded in the factory's dying unit, said Naveed Ahmed, a Karachi police officer.
Four other people died later at a hospital. The blast also injured 28 people, at least seven of them seriously, he said.
The deaths and injuries were caused by burns and debris from the boiler and the collapsing factory building, said Liaqat Memon, a doctor at a nearby hospital where victims of the blast were taken.
Ahmed said the factory's two-story building collapsed in the explosion and debris was scattered in a wide area, shattering windows at nearby buildings.
Authorities are investigating the cause of the explosion, he said.