Russian shellfire crashed into the power grid of the newly liberated Ukrainian city of Kherson, officials said Thursday, cutting electricity to desperate residents and illustrating the challenge confronting the entire country: Even as crews race to restore basic utilities, new attacks threaten to undo their work.

"The Ukrainian energy system is under constant Russian fire,” said Andriy Herus, head of a national energy and housing committee.

Moscow’s concerted assault on the plants and equipment Ukrainians rely on for heat and light as winter nears has drawn condemnation from world leaders, with some suggesting that it may be a war crime.