The three people who died were men aged 84, 85 and 87, police said in a statement. Another 34 people were injured, one of whom was in a life-threatening condition.
A section of the hospital had to be evacuated. Injured patients were treated mostly at the hospital itself, though two were taken to nearby clinics. The fire was extinguished within about 20 minutes.
Firefighters said they found several patients at the windows calling for help. People were rescued using ladders and through the building itself.
Later Sunday, police said witness interviews suggested that a 72-year-old patient may have set the fire. He was detained at the hospital on suspicion of arson.
Investigators are looking into whether mental illness was a factor, police said.
Credit: AP
Credit: AP