A fire at a retirement home in the early hours of Friday in Milan killed six people, firefighters said, with some 80 other residents hospitalized suffering from smoke inhalation.

The three-story building was reportedly housing 167 people when the fire started in the early morning hours.

"It was a hellish scene," local resident Lucia, who can see the home from her house, told reporters.

"We saw old people protecting their faces with wet rags," and windows had been cracking with the heat, she said.

The cause of the blaze was not yet known, the fire brigade said.

Over 10 ambulances, various fire trucks and a silver mortuary van could be seen outside the building in the south of the Italian city.

"Six people killed, numerous (others) suffering from smoke inhalation hospitalized. Dozens of people saved by firefighters who immediately evacuated the building," the fire brigade said on Twitter.

Some eighty people were rushed to hospital, two of whom were fighting for their lives, Milan's fire chief Nicola Micele said.

Some 14 others were in serious condition, Italian media said.

Five of the victims were women aged between 69 and 87 years old, while the sixth was a 73-year-old man, the reports said.