Seven people were killed when overnight torrential rain unleashed heavy flooding in Russia's North Caucasus region of Dagestan, officials said Wednesday.

The flooding in the ancient Caspian Sea city of Derbent affected hundreds of homes with 1,120 people in the affected area, the regional branch of the Emergencies Ministry said in a statement.

"Seven people have been killed," it said.

Devastating floods in July in the town of Krymsk at the other end of the Caucasus mountains to the west killed 172 people and raised questions about the authorities' handling of disasters.