Police said it was unclear if the fire at the Manila Pavilion Hotel and Casino, which raged for hours, started in the casino on the lower floors or in an area of the hotel that was under renovation.
TV footage showed dark gray smoke billowing from the first and second floors of the hotel as rescuers brought people out of the building.
Johnny Yu, who heads Manila's disaster-response agency, told reporters that at least six other people were overwhelmed by heavy smoke and brought to a hospital. Among the dead were two hotel security guards and a treasury officer, he said.
Yu initially said at least four people died in the fire, but other officials later said that one of those who was feared to have died was revived by doctors at a hospital and was in critical condition.
"The smoke is very heavy and, second, there's the wind that we're trying to overcome," Yu said. "Our firefighters are having a lot of difficulty."
At least 19 people were unaccounted for, but Yu said that only two, both of them security camera operators, were confirmed to have been trapped in the hotel and rescuers were trying to reach them.
Police and firefighters blocked off the areas around the hotel, which lies in the heart of Manila's tourist district, to allow dozens of firetrucks to approach and help fight the blaze.
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