MANILA (UPDATE) - Thirty-seven people were believed killed in a fire that engulfed a shopping mall in the southern city of Davao, the local vice mayor said on Sunday.

A Bureau of Fire Protection commander at the scene said the chances of the 37 surviving were "zero," Davao City Vice Mayor Paolo Duterte, who is also the President's son, wrote in a Facebook post.

The blaze started at the 4-story NCCC Mall on Saturday morning and people were trapped inside, including in a call center on the top floor, Ralph Canoy, a police officer in the district, told AFP.

Canoy said the fire was still going before dawn on Sunday morning.

"The fire started on the third floor, which houses products like fabrics, wooden furniture and plastic ware, so the fire quickly spread and it's taking a long time to put out," he said.

He said investigators believed some of those likely killed had been trapped in the call center, which operated 24 hours a day.

"It's possible that while they were working, they did not immediately notice the fire spreading," Canoy said of the call center workers.

President Rodrigo Duterte, who served as Davao mayor for about 2 decades and continues to live in the city, visited the mall on Saturday night to comfort relatives of the victims, one of his aides told AFP.

Davao, about 1,000 kms south of capital Manila, is the biggest city in southern Philippines.