A powerful gas explosion tore through a residential apartment building in Karachi on Thursday, leaving at least 16 people dead, including women and children, and injuring several others after part of the structure caved in, officials said.

The blast occurred in a residential neighborhood of Karachi, the capital of Sindh province, as residents were preparing their pre-dawn meal to mark the first day of the holy month of Ramadan, said local police chief Rizwan Patel. Rescue teams continued clearing debris in search of possible survivors trapped beneath the rubble.

Authorities had earlier confirmed 13 deaths, but the toll climbed to 16 after three more bodies were recovered from the wreckage, Patel added.

President Asif Ali Zardari conveyed his condolences to the bereaved families and instructed officials to provide the best possible medical care to the injured. He also urged a swift completion of rescue efforts and called on the Sindh provincial government to strictly enforce building regulations, ensure the safety of gas cylinders and conduct a comprehensive investigation to prevent such tragedies in the future.

Like much of Pakistan, most homes and apartment buildings in Karachi use natural gas for cooking. Due to low gas pressure, however, many households also depend on liquefied petroleum gas (LPG) cylinders.

In a similar incident in July, a gas explosion at a house in Islamabad following a wedding reception killed eight people, including the newlywed couple, according to authorities.