A fire that hit a hotel in the Philippine capital on Sunday killed at least four employees, trapped two others, and forced the evacuation of more than 300 guests, some by helicopter.

Police said it remains unclear if the fire at the Manila Pavilion Hotel and Casino, which was still raging after five hours, started in the casino or in an area of the hotel that was under renovation.

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 security guards and a treasury officer, he said.

“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 people, who work as 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 at the heart of Manila’s tourist district, to allow dozens of fire trucks to approach and help fight the blaze.