Missile attacks overnight caused damage to power facilities in the western and central parts of Ukraine, CNN's Fred Pleitgen reported from Zaporizhzhia.
The biggest attack on Ukraine's energy infrastructure comes as the country is preparing for the winter.
Ukraine said that the latest attacks were the largest massive aerial strikes on energy facilities in six months. Russia launched several cruise missiles from strategic bombers from western Russia. The Ukrainian general staff said 43 cruise missiles were launched, while Ukraine's air defense shot down 36 out of those.
The most damage was caused in western and central Ukraine, and mostly energy infrastructure was hit. Ukraine says many people were injured in one town where a hotel was hit.
At least 18 people, including a child, were injured in air strikes, Ukrainian officials told Reuters.
There are townships and cities without power and the authorities are trying to restore electricity supply as fast as they can.
"Winter is coming. Tonight russia renew missile attacks on Ukrainian energy infrastructure," Andrii Osadchuk, Member of the Parliament of Ukraine, wrote on Twitter on Thursday.
The attack occurred weeks before the winter heating season in Ukraine begins.
Earlier this week, Gas Transmission System Operator of Ukraine (GTSOU) said it is conducting large-scale preparation for the upcoming heating season.