MOSCOW, Russia (CNN) -- The death toll in a nursing home fire in northwestern Russia rose to 23 Sunday, as rescue workers discovered more bodies in the ruins, officials said.
Authorities do not yet know what caused the fire Saturday at the facility in the republic of Komi, the country's Ministry for Emergency Services said.
Firefighters several hours fighting the blaze.
President Dmitry Medvedev ordered the Russian prosecutor general's office to conduct an investigation amid reports of frequent fires at hospitals, schools and other state-run facilities.
Many Russians blame the fires on official negligence and violations of fire safety rules.
CNN's Arkady Irshenko and Zarifmo Aslamshoyeva contributed to this report.