A Ukrainian official said a young man and his 6-year-old brother had been killed when a Russian guided bomb hit a schoolyard on Thursday, after Moscow troops stepped up air strikes on the northern Sumy region bordering Russia's Kursk region.
Moscow on Tuesday accused the Ukrainian military of launching an armoured assault in the Kursk region, in one of the largest such incursions of the 29 months of the full-scale war.
Russia said it was continuing to push Kyiv forces back. The Ukrainian military did not comment on the assault.
The pair were killed in Mohrytsia village, Volodymyr Artiukh, head of the Sumy region's military administration told national TV.
He said the area had seen an unprecedented number of air strikes.
"Sumy region has never known such a large number per day," he added, referring to 56 guided bombs dropped by Russia in the past 24 hours.
Regional Ukrainian military officials on Wednesday announced mandatory evacuations of civilians from more than 20 border settlements.
