Thirty-six bodies were found inside a casino in the Philippine capital today after a masked man burst in with an automatic rifle and set fire to a gaming room, authorities said, but insisted it was not a terrorist attack.

Dozens of others were injured in a stampede as they rushed to leave Resorts World Manila, which is across a road from the Philippines' main international airport, after the man fired what police said was an M4 assault rifle and started the fire around midnight. 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.