Explosions were reported in at least three Ukrainian cities Friday as authorities said Russia launched a "major missile attack" on energy facilities and infrastructure.
Local authorities on social media app Telegram said air raid alarms sounded across the country as explosions were reported in the capital of Kyiv, southern Kryvyi Rih and northeastern Kharkiv.
Kyiv Mayor Vitali Klitschko reported explosions in at least four districts, according to the Associated Press.
"The attack on the capital continues," Klitschko wrote on social media. He urged residents to seek shelter, reminding them that subway services in the capital were suspended as people flocked to the underground tunnels for protection.
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Kharkiv Mayor Ihor Terekhov said his city is without electricity, while Kharkiv regional governor Oleh Syniehubov announced three strikes on critical infrastructure, AP reported.
Kyrylo Tymoshenko, a top official in President Volodymyr Zelenskyy’s office, reported a strike on a residential building in Kryvyi Rih.
"There may be people under the rubble," he wrote on Telegram, adding that emergency services had arrived at the building.
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National railway operator Ukrzaliznytsia reported power outages at an undisclosed number of stations in the eastern and central Kharkiv, Kirovohrad, Donetsk and Dnipropetrovsk regions due to damage to the energy infrastructure.
Trains remained in operation by switching from electric power to steam-engine power.
Russian strikes targeting energy infrastructure have been part of a new strategy to try to force Ukrainians into submission after key losses in recent months.
In contrast, some analysts and Ukrainian leaders believe Russia's losses have only strengthened Ukrainian forces as the conflict enters its tenth month.
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Russian strikes have been launched on Ukraine intermittently since mid-October, with the previous round taking place on Dec. 5.
Ukrainian authorities have reported some successes in intercepting and downing incoming missiles, rockets and armed drones.
The Associated Press contributed to this report.