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 Telegram that the city is without electricity.

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.