DAVAO CITY, the Philippines -- At least 37 people may have died in the massive fire that ravaged a shopping mall here on Saturday, authorities said on Sunday as firefighters continued battling pockets of flames 16 hours after the blaze broke.

Distraught relatives wailed in grief as Philippine President Rodrigo Duterte announced the firefighters' grim assessment on the victims' fate around 3:00 am local time.

"According to the authorities still in the area, in that situation it's difficult to believe anyone can survive. Chance of survival is zero," Archbishop Romulo Valles, president of the Catholic Bishops'Conference of the Philippines (CBCP) quoted the president as saying.

Valles told reporters outside a restaurant where the president was meeting with relatives of the missing workers.

As of 5:00 am on Sunday, at least 37 people are listed as missing following the blaze that destroyed parts of NCCC Mall of Davao, city vice mayor Paolo Duterte, the president's son, said.

The president arrived at a restaurant where the kin of the missing were gathered just across from the smoldering four-storey edifice past 9:00 pm on Saturday.

Officials said rescue workers may begin on Sunday their task of searching and retrieving the bodies.

Police said the blaze may have started at the furniture store located in the shopping center's third floor and spread to the upper floor.

Valles said firemen and rescuers were finding it difficult to penetrate the inner portions of the building due to thick smoke and searing heat as pockets of fire continued to burn.

Six workers were able to escape with injuries in the early stages of the fire which started around 9:30 am on Saturday, police said.