At least 37 persons were killed at a casino here in an attack which was claimed by the Islamic State even though the police continued to deny that the incident was terror-linked.
A lone gunman entered the Resorts World Manila in the early hours of Friday morning, firing shots from an assault rifle and setting fire to gambling tables, CNN reported.
Most of the victims were believed to have died from suffocation in the fire, said police officials.
The IS, in a statement released by Amaq news agency, claimed that its "fighters carried out" the attack. However, the militant group didn't release names or pictures of the "soldiers" who carried out that attack, which it usually does.
Rejecting the claim, police said there was "no truth" to the assertion.
"They can always claim whatever they want to claim," said Philippine National Police Chief Oscar Albayalde.
Police said repeatedly that the attack was not related to terrorism. The armed suspect forced his way into the casino around midnight, said witnesses and police.
According to security footage viewed by police, the gunman entered via the parking lot. Police later searched a car and found registration information which they didn't make public.
The attacker walked into the building, past a lone security guard who panicked when she saw the suspect's automatic rifle, a police official said.
The footage showed guests frantically running for the exits, the sound of gunshots and smoke coming from the upper floors of buildings.
Hours later, the police confirmed the gunman had committed suicide by setting himself on fire. He was found in the room, burned beyond recognition, next to a machine gun and a .380 calibre pistol.
The attacker also ransacked a room and stole gaming chips, Philippines National Police Chief Ronald Dela Rosa told CNN Philippines.
He had stuffed chips totalling 113 million pesos ($2 million) in a backpack, but it was later recovered by police. Dela Rosa added that the suspect appeared to be Caucasian.
Of the 37 victims, 13 were employees of the casino while the rest were guests. Police were yet to identify the bodies of six people, including two employees and four guests.
