A Pakistani police officer says a fire that broke out at a shoe factory in an eastern city has killed 21 people.

Senior police officer Multan Khan says six people were also injured in the blaze at the factory in Lahore, the capital of Punjab province.

He says some of the people died from suffocation while others were burned alive when the flames ripped through chemicals stored there.

He says the fire broke out when people in the building were trying to start their generator after the electricity went out. Sparks from the generator made contact with the chemicals.

Many people in Lahore have set up shoe factories at homes and in the residential areas. Most such factories are ill-equipped and often lack modern fire safety equipment.