The gunman in a deadly casino rampage in the Philippines was seen on security camera footage firing his M4 rifle in the air, setting fires and shooting at security forces during an attack that killed 38 people.

The Islamic State (IS) group has claimed responsibility for Friday's attack in Manila, but authorities say it was a botched robbery by a single gunman and there was no links to terrorism.

The man stormed into the Resorts World Manila complex and used petrol to torch gambling tables before fleeing to an adjoining hotel where he killed himself. The victims appeared to have died of smoke inhalation as they hid from the gunman, police said.

At a news conference on Saturday, authorities showed the security footage to the media and said the gunman's identity was still unknown. Police described him as an English-speaking man in his 40s, 6ft tall and armed with an assault rifle.

The taxi driver who dropped the man off at the casino said the man also spoke fluent Tagalog and appeared normal during the ride, said Manila police chief Oscar Albayalde.

He said terrorism was unlikely because the gunman did not shoot anyone.

"He could have shot everybody there," Albayalde said. "You see he was even changing magazines, he changed magazines at least three times.

"With all that ammunition, he could have killed hundreds of people inside that establishment. But he did not shoot anybody ... he just burned the casino. Burning the casino could be a diversionary tactic for his escape."

National Police Chief Ronald dela Rosa also said the attack did not appear to be terrorism, but he cautioned that authorities still know very little about the attacker.

"What if we establish the identity and there are leads that will lead toward terrorism? So our findings, our conclusion, will possibly change," he told DZMM radio.

Luchie Arguelles, 61, was playing the slots at around 12.10am on Friday when she saw the man enter the room.

"(He was) all dressed in black, burly, everything was covered, you can't even see his eyes," said Arguelles, who was about 30ft from the gunman. She said he was holding two small bottles of liquid and dousing the baccarat table.

"I said, 'He's going to burn that table, he's going to douse it,'" before she grabbed her husband's hand and started running.

The attack sent hundreds of people fleeing through the complex and into the night. More than 70 people suffered mostly minor injuries in the stampede to escape.

Philippine President Rodrigo Duterte said the casino attack was not the work of Islamic State and that the gunman was just "crazy."

He made his remarks on Saturday in the southern Philippines. It was his first comments on the attack.

Duterte said "that guy is crazy" because he stole casino chips, even though he wouldn't be able to use them.

He said the Islamic State's attacks were "more cruel and brutal. They would just simply kill people for nothing. Not even for a reason. And that's the reason why the world today has banded together to fight this scourge of terrorism, especially if you kill in the name of God. There is no rhyme or reason really".

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