Ukrainian authorities reported explosions in at least three cities Friday, saying Russia has launched a major missile attack on energy facilities and infrastructure.

Local authorities on social media reported explosions in the capital, Kyiv, southern Kryvyi Rih and northeastern Kharkiv as authorities sounded air raid alarms across the country warning of a new devastating barrage of the Russian strikes that have occurred intermittently since mid-October.

Kharkiv Mayor Ihor Terekhov said on the Telegram social media app that the city is without electricity. Kharkiv regional governor Oleh Syniehubov reported three strikes on the city’s critical infrastructure.

Kyrylo Tymoshenko, a top official in President Volodymyr Zelenskyy’s office, reported a strike on a residential building in Kryvyi Rih, warning on Telegram: “There may be people under the rubble.” Emergency services were on site, he said.

Kyiv Mayor Vitali Klitschko reported explosions in the northeastern Desnianskyi and western Holosiivskyi district, urging residents to go to shelters.

“The attack on the capital continues,” he wrote on Telegram.

The strikes targeting energy infrastructure have been part of a new Russian strategy to try to freeze Ukrainians into submission after several key battlefield losses by Russian forces in recent months.