According to Ukraine, Russia has launched more than 50 missiles targeting critical infrastructure across Ukraine, including the capital Kyiv, causing power and water shortages.
A Kyiv resident told the BBC his neighbourhood was without electricity after Monday morning’s massive attack.
In the northeastern city of Kharkiv, energy facilities were hit.
The strikes come after Russia accused Ukraine of a drone attack on its Black Sea Fleet in annexed Crimea.
Kyiv Mayor Vitaliy Klitschko said 80% of the city’s residents were left without a water supply after a damaged energy facility near the capital. He also said engineers had been urgently deployed to restore power to around 350,000 apartments in the megacity.
City authorities said “no hits were recorded” in Kyiv, even thanks to the “effective work of the air defence forces”.
On Monday morning, missile strikes were also reported in the central Vinnytsia region, Dnipropetrovsk and Zaporizhzhia in the southeast and Lviv in western Ukraine.
The Dnipro hydroelectric power station installation in the Zaporizhzhia region was also reportedly affected.
It was not immediately known if there had been any casualties.
Residents of the attacked areas have been told to stay in shelters, fearing more strikes will follow. They were also warned that “emergency power cuts” were underway across the country.
Ukrainian Air Force spokesman Yuriy Ihnat told Ukrainian television that Russia had used its strategic bombers to carry out its “massive” strikes.
The Ukrainian military later said that 44 of more than 50 X-101 and X-555 cruise missiles launched from Russia’s Rostov region and the Caspian Sea had been shot down.
Ukrainian Foreign Minister Dmytro Kuleba said, “instead of fighting on the battlefield, Russia is fighting civilians”.
Russia has recently carried out several waves of deadly missile and drone attacks, destroying nearly a third of Ukraine’s power plants and other energy-generating facilities before the cold winter spell.
Ukraine and its Western allies have repeatedly declared that targeting civilian infrastructure amounts to war crimes.