An explosion on Tuesday inside a boiler room within a factory in New Karachi Industrial Area resulted in the deaths of seven and injury to at least 16, police said.
According to Deputy Superintendent of Police (DSP) Moeenuddin, the incident took place inside an ice and cold storage factory.
He said seven people were at work inside the factory when the blast occurred.
DSP Moeenuddin said that the building has been "extensively damaged" and nearby factories have also been affected. He said many people are likely buried underneath the factory's rubble.
Rescue officials at the site said that the roof of the building caved in after the blast.
Bystanders rushed to the site to help the affected as rescue teams arrived.
Officers of the police, Sindh Rangers and Karachi Municipal Corporation are all assisting rescue efforts.
Labour minister orders inquiry
Sindh Minister for Labour Saeed Ghani noted with grave concern reports of the incident and ordered the ministry's secretary to conduct a probe.
According to a statement by the labour ministry, a safety team from the labour department has been instructed to go to the factory.
Ghani has demanded that a report on the explosion be submitted within 24 hours.
The minister also got in touch with the area deputy commissioner, said the statement, adding that officials of all relevant departments were urged to provide speedy medical assistance to all those affected by the blast.
The statement further said that Ghani directed that the heirs of the deceased be promptly notified and arrangements be made for their burial.