TOKYO, Feb. 1 (Xinhua) -- Eleven people died in a fire at a welfare facility for elderly and people with special needs late Wednesday night in the northernmost prefecture of Sapporo, local police said Thursday.

A total of 16 residents were staying at the facility for impoverished seniors and people with special needs when the fire broke out in the three-storey building at around 11:40 p.m. local time on Wednesday night.

More than 40 fire engines were dispatched to the inferno and it took firefighters 12 hours to extinguish the blaze that left the old, wooden building completely gutted.

The fire was finally extinguished just before midday on Thursday, fire officials said.

The officials said that 11 people were found dead in the building. Seven of them were found on the ground floor and four people on the second floor. No one was living on the third floor, the officials said.

First responders managed to rescue five people from the fire at the facility in Sapporo City.

Three of them, according to local media accounts, are receiving treatment in hospital for non life-threatening injuries as a result of the fire.

Police and firefighters are still trying to determine the exact cause of the fatal blaze. According to fire officials, a central area on the ground floor of the facility was burnt most severely.

Each room had been provided with a kerosene heater and a central kerosene refueling tank was kept on the ground floor of the building in a communal living space, the facility's operator, a member of the nonprofit organization Homeless Support Hokkaido Network, said.

The rooms each had a smoke alarm, but were not equipped with fire sprinklers.

By law, as with boarding houses and some lodging facilities, the operator was not legally required to provide the rooms with fire sprinklers.

According to local media reports, however, following a safety inspection in March 2014, the facility was told to improve its management of fire safety equipment.

No legal violations were found in a subsequent inspection conducted by Sapporo City fire department in December 2016.

The facility, believed to have been built around 50 years ago, had provided the requisite number of fire extinguishers and all alarms had been installed to the satisfaction of the safety inspectors.

The residents of the building, which used to be an inn and described by local media accounts as being "decrepit," were all aged between 40 and 80-years-old, with the majority of them receiving welfare assistance from the government.

They each paid 36,000 yen (329 U.S. dollars) per month in fees to stay at the facility and were provided with three meals every day.

Some of the residents suffered from dementia, while others were staying at the facility due to not having any relatives or because they needed assistance in their daily lives.

The facility's staff members do not usually stay overnight at the center, which is located less than 2 km from Sapporo railway station and 1 km from the city center.

Japan's public broadcaster NHK said that according to eyewitness accounts smoke was seen billowing out of the facility at 11:40 p.m. local time.

Other media outlets quoted witnesses as saying they heard a number of loud explosions before the building became engulfed in flames.

Police are currently working on identifying the deceased.