"In seven hours, Odesa received almost a two-month norm of rainfall. No storm sewer system can withstand such a load," the mayor of Odesa Gennadiy Trukhanov said on Telegram.

"Currently, nine people are known to have died, including one child," the State Emergency Service said in a separate post.

Hundreds of rescuers worked overnight to evacuate people from flooded areas, remove cars and pump water out of buildings.

A total of 362 people have been rescued so far, the service said.

Mayor Trukhanov acknowledged the situation was challenging but said it was "under control".

More bad weather is forecast for tomorrow.

"Work continues without a break -- both day and night," Trukhanov said.

The deadly weather adds to the challenges facing emergency services as Ukraine endures daily attacks by Russia, which controls about 20 percent of its territory three-and-a-half years after Moscow launched its large-scale invasion.

A man died Wednesday morning in a Russian attack on the southern city of Kherson, according to the local military administration.

Six people, including a policeman, were wounded in overnight strikes in the northeast region of Kharkiv, according to the national police.