Floods and landslides killed at least 103 people in southern Russia after two months' average rainfall fell in a few hours, forcing some to climb on to roofs and into trees to save themselves, police said on Saturday.
Many victims were elderly people who were asleep in the town of Krymsk when the storm broke in the agricultural region of Krasnodar overnight.
They drowned as the torrential rain turned hilly streets into driving torrents and water rose above head-height in what one official called the worst flooding for 70 years.
Five people were electrocuted when an electric transformer fell into the water in the coastal resort of Gelendzhik and some victims were swept out to sea.
The flooding damaged thousands of homes, blocked railways and roads, and halted oil and grain shipments from the Black Sea port of Novorossiisk.
"There are lots of overturned cars, even huge trucks. Brick walls have been washed away," said Vladimir Anosov, a resident of the village of Novoukrainsky near Krymsk, a town surrounded by mountains about 300 km (190 miles) northwest of Sochi where Russia will host the 2014 Winter Olympics.
"People are on the street, they are at a loss what to do. Helicopters are flying overhead, they are evacuating people from the flooded areas. The floods are really, really huge," he said by telephone.
Russian news agencies said President Vladimir Putin was expected to visit the region to inspect the damage and meet residents, some of whom criticized the rescue operations.
It was not immediately clear what the impact might be on the grain harvest, an important part of the regional and national economy.
"We found several streets with corpses covered in canvas. People there are in shock. They keep on mumbling that they had not been warned ... There are lots of Emergencies Ministry staff, but they are struggling to cope with the disaster," a reporter on Krasnodar's 9 TV channel said.
Novorossiisk, Russia's largest Black Sea port, halted crude oil shipments, a spokesman for oil pipeline operator Transneft said. The port also suspended grain exports.
Police put the death toll in the Krymsk area alone at 92 and said two had been killed in Novorossiisk and nine in Gelendzhik.
"Police are beefing up their presence to prevent mass looting," police spokesman Igor Zhelyabin said.
"The floods hit at night when people were asleep. You can't do anything about that. Many people in Gelendzhik were hit by electric shocks and some of them were washed away into the sea."
The Krasnodar region, with its coastline and high, wooded mountains, is a popular holiday destination for Russians, particularly Gelendzhik. The holiday season has just began, but it was not clear whether any tourists had been killed.
The State Hydrometeorology Agency said more rain was possible on Saturday and Sunday and Alexander Tkachov, the governor of the Krasnodar region, urged people not to panic.
"No one can remember such floods in our history. There was nothing of the kind for the last 70 years. More than 5,000 households were hit," Itar-Tass news agency quoted him as saying.
Transneft spokesman Igor Dyomin said regional transport was in a state of collapse, and all trains heading to and from Novorossiisk were suspended.
"The water has risen half a meter above the rails," Russian Railways said on its website.
The Novorossiisk port, which handles grains and metals as well as crude oil, said the outlet had cut shipping volumes.
"We are not loading grain due to the rainy weather," port spokesman Mikhail Sidorov said.
"Of course, we have 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."
Last month Transneft forecast crude exports from Novorossiisk would fall to 3.38 million metric tonnes (3.72 million tons) in July from 3.61 million metric tonnes in June.