Today's attacks are described as the heaviest bomb attack since the outbreak of war, according to the Reuters news agency.
Shortly after 2 p.m., several robot attacks took place against the Ukrainian capital, Kyiv.
According to the mayor Vitali Klitschko, several residential buildings were hit.
One person has died and large parts of the city are now without electricity, reports the AFP news agency.
During the afternoon, there have been explosions in about a dozen Ukrainian cities, including Kharkiv, Lviv, Poltava, Mykolaiv and Dnipro, writes The Guardian.
Seven million without electricity
In several parts of the country, airstrikes were carried out against energy facilities where the power supply was knocked out.
At 6 p.m., Swedish time, seven million households were without power, according to national grid operator Ukrenergo.
- This is the most massive shelling of the power system we have seen since the beginning of the war, says Infrastructure Minister Herman Halushchenko, reports Sky News.
Ukrainian President Zelensky warns that more attacks are expected during the evening.
In a video clip published on Telegram, he urges the population to stay in the shelters for a while longer.
- It is clear what the enemy wants.
Another twenty or so attacks are likely to follow.
Take care of yourselves and seek shelter in the shelters, he says in the video.
Taking place at the same time as the G20 meetings
The attacks take place at the same time as the ongoing G20 summit, where the Russian war of invasion was high on the agenda.
The Ukrainian UN ambassador Sergiy Kyslytsya writes on Twitter that the attacks are like spitting in the face of the G20 leaders.
Even the country's Prime Minister Denys Shmyhal condemns the attacks.
"The Russian terrorists have again shown their so-called willingness to negotiate today.
Another massive attack during the G20 meeting.
Residential buildings were met.
They are trying to destroy energy infrastructure.
For Russia, punishment for crime will be inevitable," he writes on Twitter.