Russia on Wednesday launched a major ballistic and cruise missile attack on regions across Ukraine, targeting energy production and compelling authorities to shut down the power grid in some areas despite freezing winter weather,

Russia’s military on Tuesday said it would retaliate against Ukraine after Kyiv attacked Russian regions by firing six US-made ATACMS ballistic missiles, six UK-made Storm Shadow cruise missiles and launching one of the biggest drone attacks to date.

The scale of the assault on Wednesday was not immediately clear, but Ukraine’s energy minister called it “massive.”