Russia's attack cut electricity to 140,000 residents in Kyiv, power company DTEK told Reuters.
Utility workers had since restored electricity to 110,000 residents, DTEK said, adding that two of its engineers had been injured.
Kyiv residents took shelter in a metro station during the Russian attack. We spoke to 21-year-old student Anna Krzhypenska, who was sheltering with her cat.
Russia says it targeted Ukraine's defense industry sites in a big overnight strike "in response to terrorist attacks".
"The strike objectives have been achieved, all designated targets have been hit," it said. Ukraine says Russian assault included 73 missiles
Ukraine's air force says Russia launched 73 missiles and 656 drones at Ukraine overnight.
In a statement on Telegram, the air force said that 40 missiles and 602 drones had been downed or neutralized.
The capital Kyiv was the main target, it said, adding that missiles and drones struck 38 sites across Ukraine.
At the site of one strike in Kyiv, Olha Mudra huddled with her six-year-old daughter Natalia in front of a destroyed residential building and damaged cars.
“There was smoke everywhere, you couldn't see anything. We couldn't understand what was happening - some kind of apocalypse?" she said.
"Everything was covered (with debris), everything in smoke, you could see nothing," she added.
The Ilsky oil refinery, in the southern Russian region of Krasnodar, caught fire after a drone attack, local authorities said on Telegram on Tuesday.
In Russia's Belgorod region bordering Ukraine, an 11-year-old boy was injured after a Ukrainian drone hit a home, local authorities said on Telegram.
Air defense systems were also repelling drone attacks over Sevastopol, a Russian naval fleet base, in Russia-occupied Crimea, authorities there said.
Reuters could not independently verify all the reports.
In Kyiv, overnight strikes killed four people and wounded 58, including children, according to the capital's mayor, Vitali Klitschko.
Six people were killed and 36 injured in a missile and drone attack on the southeastern city of Dnipro and its surroundings, regional governor Oleksandr Hanzha said on the Telegram messaging app.
All the injured were in hospital in moderate condition, he added, posting pictures of destroyed residential buildings, burnt-out vehicles and a damaged children's playground.
The attack came a day after Zelenskiy reiterated warnings of a possible major assault.
"Intelligence warnings regarding Russian strikes remain in effect. A massive strike is possible. They have prepared one," Zelenskiy said in his nightly video address.
"Our defenders are ready 24/7 to the fullest extent possible with the supplies currently available."
Russia warned last week that it intended "systematic strikes" on targets in Kyiv linked to the Ukrainian military as well as decision-making centres, and urged foreigners to leave.
It said the action was in response to a drone strike last month on a dormitory in Ukraine's Russian-held region of Luhansk, which killed 21.
Ukraine denied the attack.
Russian air attacks killed at least ten and wounded more than 60 in Ukraine early on Tuesday, authorities said.
Major Ukrainian cities such as Kyiv, Dnipro and Kharkiv were hit in the attack.
The attack came a day after Ukrainian President Volodymyr Zelenskiy reiterated warnings of a possible major assault.
Five people were killed and 25 injured in the southeastern city of Dnipro, regional governor Oleksandr Hanzha said on messaging app Telegram.
All the injured were in hospital in moderate condition, he added.
At least four were killed and 51 injured, including children, across the capital of Kyiv, Mayor Vitali Klitschko said.
A suspected missile strike on a 24-storey apartment building triggered a collapse, leaving people probably trapped under the rubble, Klitschko said.
A nine-storey apartment block was among other buildings set ablaze by suspected missile debris, he added.
Thousands of residents flooded into the Kyiv subway system seeking shelter, witnesses said.
Some people carried belongings and mattresses, as the sound of defense systems repelling Russian attacks filled the air.
Stay with us as we bring you the latest developments. (Reuters)
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