As fire began gutting the top two floors of a four-storey mall in Davao city, Mr Melvin Gaa ran back in to see if he could save people still trapped in an office on the top floor.

The 33-year-old safety officer at NCCC Mall was part of a team that had evacuated 783 workers and shoppers. But he knew dozens more were still inside a 24-hour call centre on the fourth floor of the mall.

"Instead of staying on the ground, he went up again to try to save more people," said Ms Thea Padua, the mall's spokesman.

Mr Gaa never made it back. He was the 38th victim in one of the worst fires to hit Davao city, home town of President Rodrigo Duterte. He left behind his wife Rucila and 14-year-old son Rommel Jhon.

Thirty-seven others - all employees of US-based research firm Survey Sampling International - died in the fire that tore through NCCC Mall at around 9.30am last Saturday. The blaze was put out only at 5pm the next day.

Mr Arnel Areno, 28, a stock clerk at the mall, said Mr Gaa had been living a "second life" after he survived a motorcycle accident in August. "He was lucky he escaped with just a hand injury," said Mr Areno, who had known Mr Gaa for nine years.

"I know him to be very generous. If you need something, he won't think twice about helping. If you have a problem, just tell him," he said, adding that Mr Gaa got him promoted from a casual worker to a stock clerk.

Mr Gaa had already finished work when the fire broke out at NCCC Mall, but returned to help rescue people.

"He doesn't think of himself. He just wants to help," said Mr Areno.

President Duterte, whose daughter Sara is Davao mayor, was in the city for the holidays and ordered the Justice Department to investigate the fire. "Let the truth come out... what really happened," said Mr Duterte, a former Davao mayor.

The cause of the fire remains unknown. Officials said it started near a furniture store on the third floor.

A labour group in Davao claimed that fire alarms and sprinklers were not working, citing accounts by survivors. But the mall's spokesman said this was not true. "We categorically deny the allegations that we do not have enough fire exits, extinguishers, sprinklers and designated fire escapes," said Ms Padua.

Fire bureau regional chief Wilberto Rico Neil Kwan Tiu described the building as "an enclosed space with no ventilation".

In his Facebook page, Mr Gaa had pinned a quote that said: "Respect is earned. Honesty is appreciated. Trust is gained. Loyalty is returned."

Those who knew him said he certainly deserved respect for his heroic act.