The blaze at the Marco Polo apartments in the capital Honolulu started on the 26th floor and spread to at least the 27th floor and several flats, said Honolulu Fire Department spokesman Captain David Jenkins.
The three dead were found on the 26th floor, said Fire Chief Manuel Neves.
"Paramedics are expediting emergency treatment with a triage location inside the building", Shayne Enright of the city's Emergency Medical Services department told the Star-Advertiser, which reported that two patients had been hospitalised, one in serious condition and the other considered stable.
Smoke billows from a high-rise apartment building in Honolulu, Friday, July 14, 2017.
Scores of firefighters are battling the hard blaze, which started on the 26th floor and has spread to at least the 28th floor.
Daniel Hildebrandt, a tour guide who saw the fire told CNN: "It was smoke at first and it got worse and worse. there were flames coming out of the window and people that seem to be trapped on their balcony", he said. At least 12 people needed medical help, Jenkins said.
Smoke billows from the upper floors of the Marco Polo apartment complex Friday
The Marco Polo is a large residential and commercial building with 36 stories in the main tower and a seven-story parking garage.
"It's been an orderly evacuation", said security guard Leonard Rosa, who was answering phones from the front lobby of the 31-story building.
Honolulu Fire Department said three people were being treated by emergency responders, but he did not immediately know their condition. "They were choking from the smoke", he said, adding that people told him they evacuated through dark stairwells.
And officials said a number of people in the "hot zone" have been told to stay put because they can't be evacuated safely.
Yasuda says police are yelling through megaphones for people still inside to come down.
About 100 firefighters and more than 20 fire units have been dispatched to the scene. He says there was so much black smoke he could hardly see.