Tens of thousands of people have been evacuated from parts of Russia and 10 northern regions of Kazakhstan due to flooding, authorities said.
Melting snow and ice caused much greater than normal seasonal flooding, and a dam burst contributed to a record flood surge.
An oil refinery in the city of Orsk, 1.800 kilometers southeast of Moscow, has suspended operations due to flooding.
The Kremlin has warned that water levels in some areas are rising faster than at any time in the last 100 years.
Watch the clip from Russia:
Spokesman Dmitry Peskov said President Vladimir Putin had ordered the governors of the Siberian regions of Tyumen and Kurgan, further east, to prepare for an "expected sudden rise in water levels" and "inevitable" flooding.
Orsk, the second largest city in the Orenburg region with almost 200.000 people, has been under water for days, and the level of the flood wave, according to the authorities, has risen to a record level,
The dams could not withstand the water pressure.
Sirens sound in the flooded city and the mass evacuation continues.
More than 6,8 thousand residential buildings were flooded in 39 Russian regions, according to the Russian Ministry of Emergency Situations.
The most difficult situation is in the Orenburg region.
The level of the Ural River in Orenburg rose by nine centimeters by Sunday evening, the mayor's office announced.
"According to the Orenburg hydrometeorological center, on the evening of April 7, the water level in the Ural River near Orenburg reached 864 centimeters. The dangerous level is 930 centimeters," the mayor's office warns.
The regional authorities announced that they expect the "peak" of the floods on Tuesday and stabilization only after April 20.
See photos:
In Kazakhstan, the Emergencies Ministry said on Sunday that around 12.000 people had been placed in temporary shelters.
They added that the rescuers managed to transfer about 60.000 domestic animals to safe areas.
President Kasim-Jomart Tokaev said on Saturday that this is the worst natural disaster in Kazakhstan in the last 80 years.
In a televised address, Tokaev said that the government is trying to alleviate the consequences of the floods and that all the necessary assistance will be provided to the vulnerable.
Follow us on Facebook, Twitter, Instagram, YouTube i Viber. If you have a topic proposal for us, contact us at bbcnasrpskom@bbc.co.uk
Bonus video:
