Investigators think a faulty stove was cause of the fire, and have detained a man in connection with their investigation.
At least 22 people are dead after a fire at a shelter in the Russian city of Kemerovo, in east-central Siberia.
The blaze broke out late Friday night and investigators said six people were injured in the fire, two of whom are in hospital being treated for serious burns.
Initial reports described the wooden building in the city 3,000 kilometres east of Moscow as a nursing home, but the country's Investigative Committee, which probes major crimes, later said it was a “temporary residence for persons in a difficult life situation.”
Rescue workers completed their work at the scene in the early hours of Saturday morning, and a video posted by officials showed several fire engines positioned near the small, dilapidated building. The interior of the building was completely burnt out.
According to the Tass news agency, the fire spread during the night over 180 square metres in the two-storey wooden building.
This private retirement home was "illegal", according to a police source quoted in Russian media, and the Russian Investigative Committee announced it had opened an investigation into "negligence resulting in the death of two or more people."
Investigators point to faulty stove as cause of fire
The Russian Investigative Committee had announced earlier on Saturday the opening of an investigation for, among other things, "negligence resulting in the death of two or more people".
A 31-year-old man is accused by investigators of "renting out a private house as a temporary residence to elderly people", the Investigative Committee said in a separate statement.
The alleged cause of the fire was "a faulty stove", investigators said.
"The day before the incident, the tenants informed (the landlord) that the boiler was defective, but he took no steps to repair the equipment," they complained.
"The inspection of the premises is continuing, and the objects necessary for the continuation of the investigation are being seized. Witnesses are being questioned," the statement said.
According to the emergency services, the establishment had been "identified at the end of 2021" by the authorities and was due to undergo an unannounced inspection in 2023.
The regional governor, Sergei Tsivilev, ordered "immediate" meetings between the various mayors of the Kemerovo region and "their commissions in charge of emergency situations".
He also asked that "all old people's homes, mainly private, be checked".
The town of Kemerovo had already been hit by tragedy in March 2018 when a fire at a shopping centre killed 60 people including 40 children and teenagers.