At least 34 people - including two children - have been killed after a Russian missile attack on a Ukrainian city.
The country's state emergency service said another 117 people have been injured, with 15 children among them, in the northeastern city of Sumy.
Ukraine's foreign ministry later added that one of the children injured was a baby girl born this year, saying "even newborns are targets for Russia's crimes".
Volodymyr Zelenskyy also shared videos on Telegram of the aftermath of the attack on social media, showing dead bodies in the middle of a city street near a destroyed bus.
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The Ukrainian president said on social media "only scoundrels can act like this" and that "tough reaction from the world is needed".
"Russia wants exactly this kind of terror and is dragging out this war," he added. "Without pressure on the aggressor, peace is impossible.
"Talks have never stopped ballistic missiles and air bombs. We need the kind of attitude towards Russia that a terrorist deserves."
Andriy Kovalenko, a security official who runs Ukraine's centre for countering disinformation, noted the strike came after a visit to Moscow by US envoy Steve Witkoff.
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US official: 'This is wrong'
Keith Kellogg, Donald Trump's envoy for the Ukraine war, said the attack crosses "any line of decency" and that "there are scores of civilian dead and wounded".
He added: "As a former military leader, I understand targeting and this is wrong. It is why President Trump is working hard to end this war."
In response to Mr Kellogg, Mr Zelenskyy's communications adviser, Dmytro Lytvynm asked: "Don't you think it's time to smack the Moscow mule across the nose with a 2X4?".
Later, US secretary of state Marco Rubio said the strike was "horrifying" and a "tragic reminder of why President Trump and his Administration are putting so much time and effort into trying to end this war and achieve durable peace".
UK Foreign Secretary David Lammy added he was "horrified" by Russia's "barbaric strike" on Sumy, and called for an "immediate ceasefire".
Meanwhile, EU Commission President Ursula von der Leyen said "cruelty struck again" and called the strike a "blatant violation of international law".
It came hours before a separate Russian strike killed three people in the central district of the southern city of Kherson.
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The local governor, Oleksandr Prokudin, said a 68-year-old woman was injured and died in hospital and that a 48-year-old man also died after "the occupiers dropped an explosive device from a drone".
A 62-year-old woman was also killed "as a result of the shelling".
On Saturday, a Russian guided bomb hit a house in the northeastern Ukrainian town of Kupiansk on Saturday, injuring four people.
Governor Oleh Syniehubov said on Telegram that three others could be trapped under rubble.
It comes after Russian diplomats accused each other of violating a tentative US-brokered deal to pause strikes on energy infrastructure.
"The Ukrainians have been attacking us from the very beginning, every passing day, maybe with two or three exceptions," Sergey Lavrov, Russia's foreign minister, said, adding that Moscow would provide a list of Kyiv's attacks from the past three weeks.
Andrii Sybiha, his Ukrainian counterpart, dismissed the claim saying on Saturday that Russia launched "almost 70 missiles, over 2,200 [exploding] drones, and over 6,000 guided aerial bombs at Ukraine, mostly at civilians" since agreeing to the limited pause on strikes.