Other areas in Sumy region and in southeastern Ukraine, closer to the front lines, also came under Russian attack, killing a total of six people.
"At the epicentre of the strike — a high-rise apartment building, a shop and a street," Oleh Hryhorov wrote on Telegram of the strike in Sumy.
Hryhorov said the dead included a five-year-old child and her mother. The injured were being treated in hospitals, he said, including a 13-year-old in serious condition.
President Volodymyr Zelenskiy posted pictures of the aftermath of the attack, including medics attending to the injured, a strip of pavement covered in blood along with two abandoned sandals and a building reduced to rubble. He called for Ukraine's allies to intensify pressure on Russia "so that the terror can be stopped".
Sumy region, under near-constant attacks by Russian forces, is on the Russian border. Moscow has in recent months tried to expand what it describes as a buffer zone in the region.
Earlier in the day, one person was killed when Russian forces launched glide bombs near the city of Sumy. To the southeast, more than 50 strikes involving drones, artillery and bombs killed three in Dnipropetrovsk region, including two near Nikopol, a town on the opposite bank of the Dnipro River from the Russian-held Zaporizhzhia nuclear power plant.
Twelve people were injured, Regional Governor Oleksandr Hanzha said on Telegram.
Two people were killed in a strike in the city of Zaporizhzhia, a frequent recent target of deadly attacks, Regional Governor Ivan Fedorov said. A total of 21 people were hurt. Fedorov said new attacks were launched on the city late in the evening.
The capital Kyiv was observing a day of mourning, a day after a Russian missile and drone attack killed at least 30 people in the deadliest strike on the city this year.
Meanwhile Russia's military says its forces have taken control of Kostiantynivka in eastern Ukraine, a key locality whose capture Moscow has long sought in its advance through the Donetsk region.
General Valery Gerasimov, in a report to Vladimir Putin on the conduct of the war, now in its fifth year, said the southern group of Russia's forces was "carrying out offensive operations to liberate" all of Donetsk Region.
The Defence Ministry's post on the Telegram messaging app showed what it said were scenes from the captured town, including pictures of Russian servicemen holding up national flags around shattered buildings.
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