Emergency officials said 23 of about 60 people in the building when the blaze broke out were evacuated. Emergency teams have found six dead and are searching the smoldering ruins for more bodies, the local Emergency Situations office reported.
Emergency workers were also combing a nearby forest for patients who may have fled the blaze or wandered off.
The head of Russia's top state investigation agency flew to the area to personally oversee a probe.
Russia has a poor fire safety record with about 12,000 fire deaths reported in 2012. By comparison, the U.S., with a population roughly double Russia's, recorded around 3,000 fire deaths in 2011.
Another fire at a psychiatric hospital near Moscow killed 38 people in April.
Russia's rights ombudsman Vladimir Lukin on Friday called for civil society to re-establish control over the country's mental hospitals in light of the deadly fire.
- AP