Twenty-three people have been killed and over two dozen injured in a fire at a neurological hospital in Russia’s central Voronezh region. Authorities are scouring the rubble of the wooden structure, which was destroyed by the blaze.

“By 11:00am Moscow Time (07:00am GSM) the body of the 23rd and last victim was discovered. The rescue operation has finished,” the local emergencies ministry department reported, adding that work on the site is now focused on establishing the cause of the deadly blaze. A criminal case over alleged negligence has been opened.

Под Воронежем горит психоневрологический интернат, есть жертвы https://t.co/nTJ1S0qKWcpic.twitter.com/bRkYmx8wXY — Лена Кузнецова (@okonichnikov16) December 12, 2015

The fire broke out late on Saturday night local time. The single-story 600-square- meter unit was completely engulfed and destroyed by the fire. It took firefighters about two hours to douse the flames.

When the fire started 70 patients were inside the building, along with four medical personnel. At least 29 of the patients were reportedly bedridden or had limited mobility. Twenty-three people were taken to hospital, the investigative committee of the General Prosecutor’s Office said in a statement. The local health ministry reported that three patients are in serious condition.

The neurological hospital is in the village of Alferovka, home to just over 700 people. The hospital consists of two structures and is some 230km from Voronezh, a city of just under a million inhabitants.

At the time of the tragedy the hospital catered for the needs of 140 patients, at least 50 of whom were confined to their beds, RIA Novosti reported citing the facility's staff. Those who suffered no injuries were temporarily transferred to the second unit, which had not been damaged.

The evacuation of the patients was hampered by the poor state of mind that some of them were in, one of the hospital nurses, Natalya Bytsenko, told LifeNews.

“We managed to drag people out of two wards. They didn’t realize what was happening and that they should get out. The patients just stood or sit or lay there,” she said.

Preliminary investigation established that the fire broke out in one of the hospital wards. Faulty wiring or mishandling of an open fire could be the reason, but it is too early to rule out other possible causes, including foul play, a source close to the investigation told TASS.

Voronezh region has declared Monday a day of mourning for the victims of the hospital blaze.

READ MORE: Dozens dead in psych ward fire near Moscow, 3 survive

Such tragedies are not uncommon in Russia, with dozens of deadly fires at medical facilities and care homes having claimed hundreds of lives over the last decade.

On April 26, 2013, 38 people were killed in a fire at a psychiatric hospital on the outskirts of Moscow that housed as many as 41 people. Authorities pointed to faulty electric wiring and a short circuit as the most probable cause.

Among the most horrific was a 2009 fire in the Russian Republic of Komi, where the blaze destroyed an old people’s home claiming the lives of 23 people. Only three managed to escape the inferno.

Two years prior to that, a fire in the city of Tula, again in a home for the elderly, resulted in 32 deaths. Some 247 patients, including medical staff were saved.

That same year, in March 2007, another inferno in a southern Russian care home claimed the lives of 61 people, while 35 were saved. Many of the dead were confined to their beds and unable to flee the smoke and flames.

In December 2006, a fire in a drug-rehabilitation hospital in Moscow killed 46 people, mostly patients. Many of the victims had been trapped behind locked doors and windows, which had been intended to keep them from fleeing treatment.