KYIV, Ukraine (AP) -- Russian missile strikes and shelling of energy utilities left more Ukrainian villages, towns and parts of two cities without power on Wednesday, authorities said, tightening an energy squeeze that threatens misery for millions in winter.
A nearly two-week barrage of Russian attacks with missiles, self-destructing explosive drones and other weaponry on Ukraine's critical infrastructure comes as Russian forces are being forced back on the ground.
In Kherson, among the first Ukrainian cities seized by Russian forces in the February invasion, Moscow-installed authorities are bracing for a Ukrainian assault to take it back, telling residents to expect shelling and to evacuate. Text messages Wednesday urged people to leave the southern city, Russia's state news agency RIA Novosti reported.
Moscow-backed authorities have said evacuations from occupied territories are voluntary. But in many cases, the only routes out for evacuees are to Russia.
In a rare acknowledgement of the pressure that Ukrainian troops are exerting on the ground, Russia's new invasion commander, Gen. Sergei Surovikin, on Tuesday described the situation for Russian forces in the Kherson region as "very difficult."
Kherson is one of four partly or fully-occupied regions that Russia illegally annexed last month, in an effort -- widely condemned and rejected by Western nations -- to cement its land-grabs.
Proving incapable of holding all the territory it seized and struggling with manpower and equipment losses, Russia has stepped up bombardments from the air.
The scorched-earth campaign targeting Ukrainian power plants and other key infrastructure contrasts with Kremlin tactics in the invasion's opening stage, when Russian commanders had seemingly sought to spare some utilities they perhaps thought they might later need, had they not been beaten back.
Ukrainian President Volodymyr Zelenskyy tweeted Tuesday that nearly a third of Ukraine's power stations have been destroyed since Oct. 10, causing "massive blackouts" nationwide.
Later Tuesday, in his nightly video address, Zelenskyy urged Ukrainians to make "a very conscious" effort to save power, speaking before another night where substations and other infrastructure were pounded. Zelenskyy said switching off appliances and doing other things to save power during hours of peak consumption help "the entire country."
Shelling knocked out power and water in some parts of Enerhodar, Mayor Dmytro Orlov said. The southern city is next to the Zaporizhzhia Nuclear Power Plant, which is one of the most worrisome flashpoints of the nearly eight-month invasion.
Missiles severely damaged an energy facility in the region of Kryvyi Rih, a city in south-central Ukraine, the regional governor reported. He said the strike cut power to villages, towns and to one city district.
Western nations have promised more air-defense systems to help Ukraine counter the aerial assault that is testing the resilience Ukrainians have shown since Moscow invaded.
A newly arrived German-supplied air defense system has been deployed and is performing well against the Russian strikes, Zelenskyy said in in his nightly video address.
He thanked Ukrainian soldiers who shot down missiles and Iranian-made drones that were targeted at energy facilities.
Across Ukraine, Russian strikes killed at least six civilians and wounded 16 in the latest 24 hour-period, the president's office said Wednesday. It said Russian forces attacked nine southeastern regions of Ukraine using drones, rockets and heavy artillery, focusing on energy facilities.
Four cities were attacked around the Zaporizhzhia nuclear plant, the largest in Europe, with residential buildings damaged and, in Enerhodar, where plant workers live, electricity and water partially lost.
In the eastern Donetsk region, there was also continued fighting for the city of Bakhmut.