Ukrainian President Volodymyr Zelensky on Wednesday denounced what he called an “inhumane” attack from Russia, which launched dozens of missiles and drones on Ukraine’s energy grid, killing one person and causing widespread blackouts.

The country woke up early Christmas Day to air raid sirens, shortly followed by air force reports that Russia had launched Kalibr cruise missiles from the Black Sea.

“Putin deliberately chose Christmas to attack. What could be more inhumane? More than 70 missiles, including ballistic missiles, and more than a hundred attack drones. The target is our energy system,” Zelensky said.

This was the 13th large-scale strike on Ukraine’s energy system this year, the latest in Russia’s campaign targeting the power grid during winter. The air force shot down over 50 missiles, Zelensky said.

“Unfortunately, there are some hits. As of now, there are blackouts in several regions,” the Ukrainian president said.

Engineers were working to repair the system, but private energy provider DTEK said the attack severely damaged the equipment of thermal power plants, and regional officials reported power cuts.

“Christmas morning has once again shown that nothing is sacred for the aggressor country,” said Svitlana Onyshchuk, the head of the Ivano-Frankivsk region.

She said part of the region was without electricity “at a time when we celebrate one of the greatest religious holidays — the bright Christmas.”

Ukraine is officially celebrating Christmas on Dec. 25 for a second year. The government last year changed the date from January 7, when most Orthodox believers celebrate, as a snub to Russia.

The Christmas Day attack targeted the central Dnipropetrovsk region, whose governor Sergiy Lysak said Russia was “trying to destroy the region’s power system.”