About 60 people were feared dead after a bomb struck a school in eastern Ukraine, authorities said, while Russian President Vladimir Putin prepared to lead celebrations on Monday marking the Soviet Union's victory over Nazi Germany in World War Two, Reuters reports.
Luhansk region Governor Serhiy Gaidai said the school in Bilohorivka, where about 90 people were sheltering, was hit on Saturday by a Russian bomb, setting it ablaze.
"There is almost no hope that anyone survived. The aerial bomb exploded in the middle (of the building)," Gaidai wrote on the Telegram messaging app. "In the school, there were approximately 90 people, 27 were rescued. About 60 people were probably killed."
Reuters could not immediately verify his account. There was no response from Moscow to the report.
In the besieged southern port of Mariupol, the deputy commander of the Azov regiment holed up in the sprawling Azovstal steel plant pleaded with the international community to help evacuate wounded soldiers.
"We will continue to fight as long as we are alive to repel the Russian occupiers," Captain Sviatoslav Palamar told an online news conference.
As the fighting, now in its third month, raged on, leaders of the Group of Seven industrial nations vowed on Sunday to deepen Russia's economic isolation and "elevate" a campaign against Kremlin-linked elites.
The G7 said it was committed to phasing out or banning Russian oil and denounced Putin's invasion of Ukraine.
"His actions bring shame on Russia and the historic sacrifices of its people," the group said in a statement, referring to Soviet Russia's role in defeating Nazi Germany 77 years ago.
Putin has repeatedly likened the war in Ukraine - which he casts as a battle against dangerous "Nazi"-inspired nationalists in Ukraine - to the challenge the Soviet Union faced when Adolf Hitler invaded in 1941.
Ukraine and its allies say Russia launched an unprovoked war.
In a video address, filmed in front of charred Ukrainian apartment blocks with footage of Russian missile strikes, Ukrainian President Volodymyr Zelensky said that evil had returned, but his country would prevail.
"We will overcome everything. And we know this for sure, because our military and all our people are descendants of those who overcame Nazism," Zelensky said.
Putin will preside over a parade in Moscow's Red Square of troops, tanks, rockets and intercontinental ballistic missiles, making a speech that could offer clues on the future of the war.
More than 170 civilians were evacuated from the Mariupol area on Sunday, bringing the total to around 600 given safe passage during a week-long rescue operation, the United Nations said.
In the Ukrainian-controlled city of Zaporizhzhia, about 230 km (140 miles) northwest of Mariupol, dozens of people who had fled the city and nearby occupied areas waited to register in a car park set up for evacuees.
"There's lots of people still in Mariupol who want to leave but can't," said history teacher Viktoria Andreyeva, 46, who said she had only just reached the city after leaving her bombed home in Mariupol with her family in mid-April.
"The air feels different here, free," she said in a tent where volunteers offered food, basic supplies and toys to the evacuees, many travelling with small children.
Mariupol is key to Moscow's efforts to link the Crimean Peninsula, seized by Russia in 2014, and parts of the eastern regions of Luhansk and Donetsk that have been controlled by Russia-backed separatists since then.
Russian Deputy Prime Minister Marat Khusnullin said on Telegram that he visited Mariupol on Sunday, the country's most senior government figure to set foot in the city after weeks of Russian bombardment.
A number of Western officials, including US first lady Jill Biden, Canadian Prime Minister Justin Trudeau, a German parliament head and the Norwegian foreign minister arrived in Ukraine on Sunday in a show of support.
Irish rock group U2's frontman Bono and his bandmate The Edge performed a 40-minute concert in a metro station in Kyiv on Sunday and praised Ukrainians fighting for their freedom.