Ukraine said Russia had killed civilians deliberately when it pounded the mall in Kremenchuk. Moscow said the mall was empty and it had struck a nearby arms depot.
"Russian missile hit this location precisely. De-li-be-ra-te-ly ... It is clear that Russian killers received those exact coordinates," Ukraine's President Volodymyr Zelenskiy said in an evening video address. "They wanted to kill as many people."
Authorities said around 36 people were still missing.
Further east in Lysychansk in the Luhansk region, a key battleground in Russia's assault on the industrial heartland of Donbas, the governor reported increased military action.
The situation in Lysychansk resembles that in its twin city Sievierodonetsk more than a month ago when the Russians started taking building after building, Luhansk Governor Serhiy Gaidai said on Wednesday. Sievierodonetsk fell to Russia on Saturday.
"The situation in Lysychansk is very difficult," Gaidai said earlier on television.
"The Russians are using every weapon available to them ... and without distinguishing whether targets are military or not - schools, kindergartens, cultural institutions," he said.
"Everything is being destroyed. This is a scorched-earth policy."
Russian forces are trying to surround Lysychansk, Ukraine's armed forces general staff said on Wednesday.
The mayor of the southern city of Mykolaiv, Oleksandr Senkevych, said a multi-storey residential building had been hit this morning and rescuers were working there.
Russia has denied targeting civilian areas during its four-month offensive against Ukraine. The UN says at least 4700 civilians have been killed since Russia invaded on February 24.
In the Dnipropetrovsk region, towards Ukraine's east, Governor Valentyn Reznychenko said bodies of a man and a woman had been found buried under the rubble of a transportation company office that was hit by a Russian missile on Tuesday.
Separately, Russia-installed officials said their security forces had detained Kherson city mayor Ihor Kolykhayev on Tuesday after he refused to follow Moscow's orders.
In the past few days, Ukrainians have also described attacks in the southern region of Odesa and Kharkiv in the northeast.
Finland and Sweden on Tuesday moved a step closer to joining the Western NATO military alliance, whose members have provided Ukraine with weapons, after Turkey dropped its opposition to their membership.
The Kremenchuk attack drew a wave of global condemnation.
"We have run out of words to describe the senselessness, futility and cruelty of this war," UN political affairs chief Rosemary DiCarlo told the Security Council.
While Kyiv said there was no military target in the area, Russia's defence ministry said its missiles had struck a nearby arms depot storing Western weapons, which exploded, causing the blaze that spread to the nearby Kremenchuk mall.
Moscow's assertion the mall was empty was contradicted by wounded survivors such as Ludmyla Mykhailets, 43, who said she had been shopping there with her husband when the blast threw her into the air "head first".
Zelenskiy accused Russia of being a "terrorist state" at the United Nations, urging the Security Council to expel Moscow from the UN. Russia accused Zelenskiy of using the address as a "PR campaign" for weapons.
The leaders of the Group of Seven nations have announced a new approach - leaving Russian oil on the market while imposing a cap on its price.
The US also imposed sanctions on more than 100 new targets and banned new imports of Russian gold, acting on commitments made by the G7.
In a rare public questioning of Russia's rationale for the war by one of its richest men, aluminium tycoon Oleg Deripaska told reporters in Moscow: "I think that destroying Ukraine would be a colossal mistake, including for us."
