Family members of the missing lined up at a hotel across the street where rescue workers had set up a base after Monday's strike on the busy mall in Kremenchuk, southeast of Kyiv.
More than a 1,000 people were inside when two Russian missiles slammed into the mall, Ukrainian President Volodymyr Zelenskiy said. At least 16 people were killed and 59 injured, Ukraine's emergency services said.
"This is not an accidental hit, this is a calculated Russian strike exactly onto this shopping centre," Zelenskiy said in an evening video address. He said the death count could rise.
More than 40 people had been reported missing, Ukraine's prosecutor general's office said.
A survivor receiving treatment at Kremenchuk's public hospital, Ludmyla Mykhailets, 43, said she was shopping with her husband when the blast threw her into the air.
"I flew head first and splinters hit my body. The whole place was collapsing," she said.
"It was hell," added her husband, Mykola, 45, blood seeping through a bandage wrapped around his head.
Russia has not commented on the strike but its deputy ambassador to the United Nations, Dmitry Polyanskiy, accused Ukraine of using the incident to gain sympathy ahead of a June 28-30 summit of the NATO military alliance.
"One should wait for what our Ministry of Defence will say, but there are too many striking discrepancies already," Polyanskiy wrote on Twitter.
The United Nations Security Council will meet Tuesday at Ukraine's request following the attack. U.N. spokesperson Stephane Dujarric said the missile strike was "deplorable".
Leaders of the Group of Seven (G7) major democracies, at a summit in Germany, said the attack was "abominable".
"Russian President Putin and those responsible will be held to account," they wrote in a joint statement tweeted by the German government spokesperson.
Battle For Lyschansk
Elsewhere on the battlefield, Ukraine endured another difficult day following the loss of the now-ruined city of Sievierodonetsk after weeks of bombardment and street fighting.
Russian artillery pounded Lysychansk, Sievierodonetsk's twin city across the Siverskyi Donets River.
Lysychansk is the last big city still held by Ukraine in eastern Luhansk province, a main target for the Kremlin after Russian troops failed to take the capital Kyiv early in the war.
A Russian missile strike killed eight and wounded 21 others in Lysychansk on Monday, the area's regional governor Serhiy Gaidai said. There was no immediate Russian comment.
Ukraine's military said Russia's forces were trying to cut off Lysychansk from the south.
Rodion Miroshnik, ambassador to Moscow of the Luhansk People's Republic, said Russian troops and their Luhansk Republic allies were advancing westward into Lysychansk and street battles had erupted around the city's stadium.
Fighting was on in several villages around the city, and Russian and allied troops had entered the Lysychansk oil refinery where Ukrainian troops were concentrated, Miroshnik said on his Telegram channel.
Reuters could not confirm Russian reports that Moscow's troops had already entered the city.
Russia also shelled the city of Kharkiv in northeast Ukraine on Monday, hitting apartment buildings and a primary school, the regional governor said.
The shelling killed five people and wounded 22. There were children among those wounded, the governor said.
'As Long As It Takes'
Moscow denies targeting civilians in what it calls a "special military operation" in Ukraine, but Kyiv and the West have accused Russian forces of war crimes.
The war has killed thousands, sent millions fleeing, and triggered spikes in global food and energy prices.
During their summit in Germany, G7 leaders, including President Joe Biden, said they would keep sanctions on Russia for as long as necessary and intensify pressure on President Vladimir Putin's government and its ally Belarus.
The United States also said it was finalizing another weapons package for Ukraine that would include long-range air-defence systems.
Zelenskiy asked for more arms in a video address to the G7 leaders, U.S. and European officials said. He requested help to export grain from Ukraine and for more sanctions on Russia.
The G7 nations promised to squeeze Russia's finances further - including a cap on the price of Russian oil that a U.S. official said was "close" - and pledged up to $29.5 billion more for Ukraine.
The White House said Russia had defaulted on its external debt for the first time in more than a century as sanctions have effectively cut the country off from global finance.
Russia rejected the claims, telling investors to go to Western financial agents for the cash which was sent but bondholders did not receive.
(Reporting by Reuters bureaux; writing by Stephen Coates; editing by Himani Sarkar)
