At least 34 people are dead after a gunman burst into a Manila casino, firing shots and setting gaming tables alight, Philippine media has reported, in what officials say was a botched robbery attempt.

Police say the unidentified gunman killed himself after firing at armed officers searching the still-smoking Resorts World Manila entertainment complex hours after the drama that began shortly after midnight.

Many died of smoke inhalation in the chaos as guests and staff tried to flee choking smoke at the complex, according to a report by ANC News channel, quoting Bureau of Fire Protection sources.

Resort owner Travellers International Hotel Group Inc says authorities are still seeking details.

"We have been informed of several casualties, the number and identities of whom have yet to be determined," it said in a statement.

Doused in gasoline

Around dawn, the body of the suspected gunman was found in a hotel room in the complex, which is close to Ninoy Aquino International Airport and an air force base, police said.

"He burned himself inside the hotel room 510," national police chief Ronald dela Rosa told a media conference. "He lay down on the bed, covered himself in a thick blanket and apparently doused himself in gasoline."

Officials say at least 54 others were hurt, some seriously, as they rushed to escape what at first had been feared as a militant attack.

Dela Rosa told DZMM radio the lone gunman had not aimed his assault rifle at people and may have been trying to steal casino chips.

Videos posted earlier on social media showed people fleeing as several loud bangs were heard.

"Even the security personnel panicked. Maybe because of the heavy firearm, they can't put up a fight so they prioritised life and safety," Jeff Santos, a high roller at Resorts World Manila, told a Philippine radio station. "Definitely us patrons we did not expect that, everyone ran away."