MANILA — The gray smoke that belched for hours from a popular hotel-casino in Manila was initially dismissed by the police as the work of a disgruntled gambler with a bottle of gasoline. But as day broke over the Philippine capital on Friday, investigators discovered dozens of bodies, upending the government’s explanation of the fire and raising questions about the identity and motives of someone responsible for one of the country’s largest mass killings.

The first victims, identified as 22 guests and 13 employees of Resorts World Manila, appeared to have died of smoke inhalation, the police said, though autopsies had not yet been conducted.

The fire was started in the early hours of Friday morning, when a man carrying an assault rifle and a two-liter soda bottle filled with gasoline fired shots at a television and set gambling tables ablaze, sending patrons and workers into a panic. Some fled through the exits, and others jumped from second-floor balconies. But others hid in restrooms and gambling rooms, where they were overcome by smoke.

“This is also a very difficult time for all of us here in Resorts World Manila,” Stephen Reilly, the resort’s chief operating officer, told reporters. “We consider our guests, patrons and employees as our family.”