A large-scale Russian missile and drone attack damaged power plants and caused blackouts for more than a million Ukrainians on Friday morning, in what Ukrainian officials said was one of the war’s largest assaults on energy infrastructure.

At least three people were killed in the assault, and 15 others were injured, according to the office of Ukraine’s general prosecutor.

The strikes came as ​the Kremlin escalated its rhetoric over the conflict, saying that Russia was “in a state of war” in Ukraine — and moving beyond the euphemism “special military operation” — because of the West’s heavy involvement on the Ukrainian side.

In Kharkiv, Ukraine’s second-largest city, traffic lights were not working and the water supply was disrupted. A fire raged at the country’s largest hydroelectric dam, in the southeastern city of Zaporizhzhia. A few dozen miles to the southwest, a power line supplying a Russian-occupied nuclear power plant was temporarily knocked out.

“The enemy is now launching the largest attack on the Ukrainian energy sector in recent times,” Herman Halushchenko, Ukraine’s energy minister, said on Facebook. “The goal is not just to damage, but to try again, like last year, to cause a large-scale failure of the country’s energy system.”