As many 11 people were killed and scores injured by falling trees and debris from buildings as a storm swept through Moscow on Monday, the national Investigation Committee, which is looking into the deaths, said.
Moscow mayor Sergei Sobyanin said on his Twitter account that more than 40 people had asked for medical assistance. He said hundreds of trees were toppled, as meteorologists reported winds of up to 80 kmh (50 mph).
"The hurricane was unprecedented for Moscow," TASS news agency quoted him as saying.
News agencies reported falling trees had blocked roads and metro railways.
Moscow is usually spared such extreme weather, though high winds are not unusual in the region in the summer months.
The death toll was the highest due to storms in the capital in a single day for almost 20 years. Between eight and 11 people died in storm in the capital in 1998.