Four people were killed with three others unconscious after a fire broke out early Sunday at an apartment building in Kobe, western Japan, authorities said.

Firefighters received a call around 1:35 a.m. from a neighbor of the three-story housing complex in Hyogo Ward of the city saying that black smoke was coming out of a window on the first floor.

Firefighters investigate an apartment building in Kobe, western Japan, on Jan. 22, 2023, after a fire there earlier in the day. (Kyodo)

The four, who were confirmed dead at the scene, were identified as Katsuhiro Yamaguchi, 77, Tadao Murakami, 86, Toshihiko Kimura, 78, and Masayuki Tsuda, 79, according to police and residents. They all lived on the first floor of the complex.

Of the other four men taken to hospital, three of them aged in their 60s and 70s remain unconscious while a man in his 40s was revived, the police said.

All eight individuals were found on the first floor of the building, where some residents have mobility issues and are visited by caregivers, they said.

The complex was built in 1963 and has around 30 residents, many of whom live alone, with pension recipients and people living on welfare among the inhabitants, according to residents and other sources. The units were mainly for single occupancy.

Several of the residents smoked despite the building having a no smoking rule.

According to the local fire department and residents, fire alarms and extinguishers were installed on each floor, with the alarms believed to have been triggered during the fire.

No issues were found in the latest inspection of the building's fire extinguishing system last month. Sprinklers, a legal requirement only for apartment buildings with 11 floors or more, were not installed in the complex.

A 54-year-old man who lives on the second floor woke up to the sounds of a woman who was passing by screaming that there was a fire.

"My room was completely white with smoke and I ran out," the man said. "A room on the first floor was burning bright red. I would have been in danger if I hadn't noticed."

Some 26 square meters of the 300 square meter building were burned, with the damage confined to the first and second floors, the authorities said. The fire was mostly extinguished after about an hour.

Photo shows a predawn fire at an apartment building in Kobe, western Japan, on Jan. 22, 2023. (Photo courtesy of a passer-by)(Kyodo)