Authorities declared a state of emergency in Dagestan after torrential rainfall flooded streets in the regional capital Makhachkala, damaging homes, vehicles and infrastructure.
Local leader Sergey Melikov said some areas recorded more than 50mm of rain, an unusually high level for recent years.
Russia’s emergency ministry said around 3,000 people had been evacuated as floodwaters cut electricity to more than 130 settlements and destroyed several bridges.
Neighbouring Chechnya has also been affected, with hundreds of homes flooded in the Gudermes district and about 500 residents evacuated.
Meteorologists say the rain is expected to ease, but recovery efforts are continuing across the region.