MANILA — It started as a mass panic at the biggest hotel-casino resort in the Philippines over fears of an Islamic State terrorist attack. It was thought to have ended with the police saying the only fatality was the lone assailant, a gambler with a grudge who shot out TV screens and set fires on game tables before killing himself.

Then came the stunning news Friday afternoon: At least 36 people had been found dead, suffocated in the chaos.

The gunman had burst into the casino at Resorts World Manila, stuffing a bag with casino chips, then dousing the tables with gasoline and setting them aflame.

The attack ignited fears of terrorism. Authorities, however, expressed doubt.

‘‘He would have shot all the people gambling there’’ if it had been terrorism, Philippine National Police Chief Ronald Dela Rosa said. ‘‘But he did not hurt anyone.’’

Police initially said about 70 people suffered minor injuries in the stampede to escape. The only gunshot wound was to a guard who accidentally shot himself when the suspect entered a room.

Several hours later, however, Metropolitan Manila police chief Oscar Albayalde said 36 people suffocated from the smoke. Their bodies were found by firefighters.

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