DAVAO, Philippines -- Philippine firefighters have found all 37 bodies of employees of a U.S.-based company who were trapped in a blaze that gutted a shopping mall in southern Davao city on Saturday.

Mayor Sara Duterte-Carpio said that firefighters initially found one body at the NCCC Mall on Sunday, but that extreme heat and thick smoke prevented them from retrieving the bodies of the 36 other employees until Monday.

Reuters news agency reports that six people were rescued at the scene and taken to a local hospital.

Get Breaking News Delivered to Your Inbox

Senior Superintendent Wilberto Rico Neil Kwan Tiu, regional director of the Bureau of Fire Protection, relayed the news to the employees' relatives, who broke into tears. They were told the bodies would be identified by authorities then turned over to their families.

People watch as smoke rises from burning mall's 3rd floor, in Davao City, Philippines, in this Dec. 23, 2017, picture obtained from social media. Reuters

All the dead were employees at a call center on the top floor of the four-story mall and run by U.S.-based Research Now SSI, which employs about 500 people. Its chief executive officer, Gary Laben, said the company would help with funeral arrangements and create a fund for contributions for the victims' families.

"This terrible tragedy has left us with heavy hearts," Laben said.

Duterte-Carpio and Tiu spoke at a Mass outside the burned mall, where the fire broke out Saturday morning on the third floor, where clothes, appliances and furniture are sold. The fire started after a storm hit Davao and flooded parts of the city.

Except for a grocery store on the ground floor and the call center on the top floor, the shopping areas were still closed to the public when the fire started mid-morning, preventing a bigger tragedy amid the peak Christmas shopping season.

President Rodrigo Duterte went to the scene of the fire and met with relatives of the trapped office employees late Saturday. He served as Davao mayor for many years before being elected to the presidency last year.