At least 78 people have been killed after torrential rains leading to flash floods swept through parts of the south Russian Krasnodar region.
Reports said the floods came at night without warning, catching local residents by surprise.
Crude oil shipments from the Black Sea port of Novorossiisk have suspended.
Officials say emergency teams have been sent from Moscow by plane and helicopter.
Television pictures showed people scrambling onto their rooftops to escape.
At least 67 people including a 10-year-old boy died in the town of Krymsk, at least nine in Gelendzhik and two in Novorossiisk.
Hundreds of properties have been flooded and the Krasnodar-Novorossiisk road was cut. The transport system in the region is said to have collapsed.
A statement by the Krasnodar regional administration said altogether 13,000 people had been affected by the floods.
Emergencies Minister Vladimir Puchkov is on his way to the region.
Up to 1,000 rescuers are involved in searching for victims and evacuating survivors.
"The floods were very strong. Even traffic lights were ripped out," regional police spokesman Igor Zhelyabin told AFP news agency, adding that evacuations were under way.
Regional governor Alexander Tkachev tweeted after flying over the affected area that there was "something unimaginable" going on in Krymsk.
He said, quoted by the Russian RIA news agency, that the flooding was the worst in the region for 70 years but the situation should "stabilise" in the next few hours.
Anna Kovalevskaya, who says she has relatives in Krymsk, told the BBC her family was caught unawares by the floods.
"The water started flooding in at 2am[22:00 GMT Friday]," she said.
"People were running out into the streets in their underwear and wrapping their children in blankets. People were only able to save their passports.
"There is no electricity and the shops are shut. Many people have lost everything and are in a state of panic."
Oil pipeline operator Transneft said it had halted crude shipments out of Novorossiisk but that its infrastructure in the port had been unaffected by the weather.
"Of course, we limited shipments, the port is located in the lower part of town, the whole landslide has moved towards it. As we speak, the rain has started again," spokesman Vladimir Sidorov told Reuters news agency.