A severe snowstorm injured 13 people in Ukraine’s southern Odesa region, causing power outages in more than 1,600 settlements across the country and forcing authorities to close over a dozen motorways to vehicles, officials said on Monday.

The extreme weather comes as tens of thousands of troops man front-line positions in the 21-month-old war with Russia amid fears Moscow could attack the power grid with air strikes this winter.

“In the Odesa region, eight people got hypothermia and five people were injured as a result of falling trees,” the state emergency service said on the Telegram messenger.

1,638 settlements in 17 regions of Ukraine remained without power, most of them in the central Kyiv and southern Odesa and Mykolaiv regions, Oleksandr Khorunzhyi, a press officer of the state emergency service, told a press conference.

Nearly 1,700 cargo trucks were stuck and 1,130 cars had to be towed away amid snow drifts that in some places were two metres (6.56 ft) high, the service said on Telegram messenger.

12 motorways remained closed as over 1,200 rescue workers were involved in a massive clean-up effort, the service added.

Ukraine’s largest private energy provider, DTEK, said early on Monday that it had been able to restore power to nearly 250 settlements.

On Sunday, the mayor of the Black Sea port of Odesa urged residents to stay at home, and authorities warned that water supplies were being interrupted by power cuts that stopped pumps from working.

“Weather conditions have stabilized, which makes it possible to speed up rescue operations… By the end of the day, we hope to free all people and clear key routes,” the Odesa regional governor Oleh Kiper said on Monday in comments on Telegram.

Ukraine’s border service also said on Sunday that Moldova had temporarily suspended vehicle access to its territory from two crossing points in the Odesa region.

In the capital Kyiv, city officials had to replace the country’s largest flag as the weather had caused a tear.