A three-alarm condo fire in the Keeaumoku Street area Sunday displaced dozens of residents and sent three people to a hospital.

About 50 firefighters responded at about 10:30 a.m. to the third-floor fire at 620 Sheridan St. and found heavy smoke coming from the unit and flames lapping up to the unit above, said Honolulu Fire Department Capt. David Jenkins.

Firefighters, using a water cannon, brought the blaze under control in about 15 minutes, he said. Firefighters also escorted several residents off the floor where the fire started.

Paramedics treated and transported a 49-year-old man and two women, ages 58 and 88, to a hospital in stable condition because of smoke inhalation, an Emergency Medical Services report said.

Firefighters evacuated the building’s 32 one-bedroom units, and hours later dozens of residents were still waiting on the sidewalk across the street. An American Red Cross volunteer told them no one would be allowed back into the building Sunday because firefighters determined the air quality was hazardous. The Red Cross was assisting with shelter.

Scott Bolter, who lives in the unit where the fire started, said he woke up from his sleep in the living room to flames and black clouds of smoke coming from a bedroom. He said he didn’t know how the fire started.

Bolter said he couldn’t see more than 2 feet in front of him because of the smoke and that he immediately helped his mother out of the unit.

The resident manager, who gave only her first name, Erika, said she ran into Bolter while descending the smoke-filled stairwell to escape. Bolter appeared dazed and was sitting on the ground, propping open the stairwell door, allowing a draft to enter and feed the flames, she said.

Another resident shouted at him to move, and Bolter began to move away from the door, she said.

Bolter said he was holding the door open to clear the hallway of thick black smoke in case anyone was trying to escape.

“It was the worst thing he could do,” Erika said after the fire.

Jenkins said residents should close doors behind them to limit the flow of oxygen to a fire. Stairwell doors, he said, are designed to automatically close and keep smoke out of the stairwells, and that residents shouldn’t prop them open.

“All we want people to do is get out,” he said.

In addition, Jenkins urged residents to practice evacuation routes on a regular basis and to have backup plans for escaping.

Resident Bradford Yamamoto said the heavy smoke trapped three residents on the third floor, and two of them waited on their lanai for firefighters as smoke wafted out of their unit.

“It was so sad because we’re here and we couldn’t do anything,” he said. He said the three third-floor residents were the ones who were taken to a hospital.

Jenkins said the cause was under investigation.