The burnt body of the gunman was found in a hotel room inside the complex about five hours later, police chief Ronald dela Rosa said.

Dela Rosa said the gunman only fired at a television screen and did not take aim at any people.

But police later reported finding 36 bodies in the casino who they said died from inhaling smoke that had become toxic because of the carpet on the gaming room floors.

“The victims who suffered from suffocation went up to 36,” Manila police chief Oscar Albayalde told reporters.

The gunman initially disappeared into the chaos of smoke and running people, leading to a manhunt through the complex that ended just after dawn when he was found dead in a hotel room, according to dela Rosa.

“He lay down on the bed, covered himself with a thick blanket, apparently poured petrol on the blanket and burned himself,” dela Rosa said.

Before the gunman had been killed and police had confirmed any motive, there was an unconfirmed claim of responsibility from the Islamic State group. US President Donald Trump also branded it a “terrorist attack”.

Albayalde also said that the gunman appeared to be a foreigner.

But he and dela Rosa insisted it was most likely a robbery gone wrong, saying the man did not shoot at anyone and appeared to be intent just on stealing gambling chips.

“For now, we can say that this is not an act of terror. There is no element of violence, threat or intimidation that leads to terrorism,” dela Rosa said.

Presidential spokesman Ernesto Abella also insisted that it was not an act of terror.

Dela Rosa said the man, acting alone, walked into one of the gaming rooms and fired the rifle at a large television screen, then poured gasoline onto a gambling table and set it alight.

He said the man then fired again at a stock room containing gambling chips and filled a backpack with chips worth 113 million pesos (US$2.3 million).

The man left the room and went upstairs to the hotel section, but left the backpack, according to dela Rosa.

The police chief said 18 of 54 injured people were in hospital. He said the others sustained only minor injuries.

People inside the casino recounted a terrifying ordeal when the shooting broke out.

“I was about to return to the second floor from my break when I saw people running. Some hotel guests said someone yelled ‘ISIS’,” Maricel Navaro, an employee of Resorts World, told DZMM radio.

ISIS is another acronym for Islamic State.

“When we smelled smoke, we decided to go for the exit in the car park. That’s where we got out. Before we exited, we heard two gunshots and there was thick smoke on the ground floor,” Navaro said.

Outside the complex, relatives of people caught inside waited on Friday to hear news of their loved ones.

“Our daughter called us past midnight saying she was in the VIP section of the casino and there was smoke and they were suffocating,” said Gil Yongco, 42.

“We are very worried about her. We haven’t heard from her.”

Philippine President Rodrigo Duterte imposed martial law last week across the southern region of Mindanao to crush what he said was a rising threat of IS there.

He made the move shortly after militants went on a rampage through the southern city of Marawi, which is about 800km south of Manila.

Security forces are still battling the militants in Marawi, and the clashes there have left at least 171 people dead.

Duterte said last week he may need to declare martial law across the rest of the country if the terrorism threat spread.