Russia's bombing of a school in the eastern Ukrainian village of Bilohorivka killed two people and left 60 in the debris feared dead, the governor of the Luhansk region said on Sunday.
Governor Serhiy Gaidai said Russian forces dropped a bomb on Saturday afternoon on the school where about 90 people were sheltering, causing a fire that engulfed the building.
"The fire was extinguished after nearly four hours, then the rubble was cleared, and, unfortunately, the bodies of two people were found," Gaidai wrote on the Telegram messaging app.
"Thirty people were evacuated from the rubble, seven of whom were injured. Sixty people were likely to have died under the rubble of buildings."
Reuters could not immediately verify the report.
Ukraine and the West have accused Russian forces of targeting civilians and war crimes, charges Moscow rejects.
Russia's 10-week-old war on Ukraine has killed thousands, destroyed cities and driven 5 million Ukrainians to flee abroad.
The besieged port city of Mariupol, a strategic target for Russian forces, has been virtually destroyed, with the last 300 civilians trapped in the bombed-out Azovstal steelworks evacuated on Saturday. Evacuation efforts will now focus on getting the wounded and medics out of the steelworks.
Ukrainian fighters in the plant have vowed not to surrender and Russian forces are seeking to declare a victory in the prolonged battle for the vast plant in time for Monday's Victory Day celebrations in Moscow, which commemorate the Soviet Union's triumph over Nazi Germany in World War II.
The Soviet-era Azovstal steel mill, the last holdout for Ukrainian forces in the key port city, has become a symbol of resistance to the Russian effort to capture swaths of eastern and southern Ukraine.
US President Joe Biden and other G7 leaders are to hold a video call with Ukrainian President Volodymyr Zelenskiy on Sunday in a show of unity ahead of Victory Day, in which President Vladimir Putin typically inspects a massive military parade in Moscow.
"Putin's brutal attack is not only causing untold devastation in Ukraine – it is also threatening peace and security across Europe," British Prime Minister Boris Johnson said in a statement on Saturday pledging more military aid.
Britain pledged to provide a further 1.3 billion pounds ($1.6 billion), double its previous spending commitments and what it said was the country's highest rate of spending on a conflict since the wars in Iraq and Afghanistan.
Putin's Victory Day speech could offer clues on the future of the war he launched on February 24 with an unsuccessful assault on the capital, Kyiv. Russia's efforts have been plagued by logistical and equipment problems and high casualties in the face of fierce resistance.
US Central Intelligence Agency Director William Burns said Putin was convinced "doubling down" on the conflict would improve the outcome for Russia.
"He's in a frame of mind in which he doesn't believe he can afford to lose," Burns told a Financial Times event.
Other observers suggest Putin may declare mission accomplished. Ukraine's defence intelligence agency has cited reports that Kremlin were in Mariupol preparing for a Victory Day parade in the devastated city.
The Kremlin did not respond to requests for comment on what Putin might say in the speech, to be delivered from the Red Square tribune in front of Vladimir Lenin's Mausoleum.
Moscow calls the war a "special military operation" to disarm Ukraine and rid it of anti-Russian nationalism fomented by the West. Ukraine and the West say Russia launched an unprovoked war.
Mariupol, which lies between the Crimean Peninsula seized by Moscow in 2014 and parts of eastern Ukraine taken by Russia-backed separatists that year, is key to linking the two Russian-held territories and blocking Ukrainian exports.
Ukraine's general staff said on Sunday that Ukrainian units near the Azovstal plant continued to be blockaded and Russia continued its assault using artillery and tanks in Mariupol.
Russia's offensive in eastern Ukraine aims to establish full control over the Donetsk and Luhansk regions - where pro-Russian separatists have declared breakaway republics - and maintain the land corridor between these territories and Crimea.
Ukraine’s forces in the two regions repulsed nine enemy attacks, destroying 19 tanks, 20 combat vehicles and one unit of enemy special engineering equipment, said the general staff on Sunday. Reuters could not immediately verify the reports.