KARACHI — The death toll from a fire at a shopping mall in Pakistan's largest city Karachi rose to 21 Monday morning after rescue teams recovered more bodies during a search operation, officials said.

A firefighter was among the dead and rescuers are racing to find dozens more still missing.

The blaze erupted late Saturday night at Gul Plaza, a multi-story shopping mall located on Jinnah Road.The building housed 1,200 stores and spanned 8,000 sq m (86,111 sq ft).

Authorities launched a search operation amid concerns that people might still be trapped inside the building.

It took firefighters more than 24 hours to put out the blaze in Gul Plaza that started Saturday night

Parts of the building have collapsed, with officials saying the debris and lack of ventilation were hampering rescue efforts.

"Almost the entire building was already engulfed in flames", by the time rescuers arrived at the site on Saturday night, local emergency services said.

Sixty people have been reported missing by their families, who have gathered outside what remains of the centre, waiting anxiously for news of their loved ones. Administrators for the city have set up a desk to register the names and details of the missing.

Hassan Khan, a spokesperson for Rescue 1122 in Karachi, told BBC Urdu the fire spread rapidly because of the presence of flammable materials such as plastic foam, cloth, and perfume in the building.

By Sunday evening, various parts of the Gul Plaza were charred and reduced to rubble. Rescuers told Reuters news agency that the whole building could come down.

Cranes have been deployed to shift what remains of the partially collapsed building, in the hope of recovering more bodies. However, rescuers are still waiting for the structure to sufficiently cool down so they can conduct a thorough search.

At least 26 of those reported missing were last seen inside the building, according to the locations of their phones, a police official told the BBC.

Zain, a shopkeeper at Gul Plaza, told BBC Urdu that hundreds of people were inside the building when the fire broke out on Saturday.

"My shops were burning before my eyes. We couldn't even get the goods out of those shops.

"There are still many people inside, I have many friends who are out of contact," he said.

Another onlooker said shopkeepers had tried to use fire extinguishers, but the intense blaze was uncontainable.

Pakistan President Asif Ali Zardari expressed his condolences and told the government of Sindh province, where Karachi is based, to conduct a comprehensive review of safety arrangements in commercial and residential buildings across the area. — Agencies