Heartbreaking images show injured pregnant women in the rubble after a Russian strike on a Ukrainian maternity hospital.
The attack, which is reported to have left at least 17 people wounded, has been branded an "atrocity" by President Volodymyr Zelensky.
It happened in the port city of Mariupol, with the bombing prompting fresh calls for Western nations to impose a no-fly zone.
Mr Zelensky posted footage online showing the damage from what he said was a "direct strike" on the hospital, with windows blown out and debris strewn through the corridors.
"People, children are under the wreckage. Atrocity!" he tweeted.
"How much longer will the world be an accomplice ignoring terror? Close the sky right now! Stop the killings!
"You have power but you seem to be losing humanity."
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Foreign minister Dmytro Kuleba called it a "petrifying war crime", as he pleaded for allies to supply Ukraine with aircraft.
Video from the scene shows a destroyed ward room with its windows blown out and ceiling partially collapsed.
More footage showed a car park covered in rubble and the smouldering wrecks of vehicles as injured families evacuated into the freezing air while snow fell.
As details of the strike emerged, Boris Johnson tweeted: "There are few things more depraved than targeting the vulnerable and defenceless."
He said the UK was considering more support for Ukraine to defend itself against airstrikes and would hold President Vladimir Putin to account "for his terrible crimes".
At least 1,170 civilians have been killed in Mariupol since the start of the Russian invasion, according to Ukrainian authorities.
The United States says it has seen indications that Russia's military is using so-called "dumb bombs" - unguided missiles which greatly increase the risk of missing targets.
A senior US defence official told Reuters: "We do have indications that the Russians are in fact dropping some dumb munitions."
Earlier Defence Secretary Ben Wallace told the MPs that the Ministry of Defence was looking at whether they could supply anti-aircraft missiles as well as more anti-tank weapons.
In Washington, Foreign Secretary Liz Truss said the strike was "absolutely abhorrent", but continued to reject calls from the government in Kyiv for a no-fly zone.
"The reality is that setting up a no-fly zone would lead to a direct confrontation between Nato and Russia, and that is not what we're looking at," she told a joint news conference with US Secretary of State Antony Blinken.
"What we're looking at is making sure that the Ukrainians are able to defend their open country with the best possible selection of anti-tank weapons and anti-air defence systems."
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Mr Blinken said US involvement in a no-fly zone could "prolong" the conflict, making it "even deadlier".
"Our goal is to end the war, not to expand it, including potentially expanding it to Nato territory," he said.
"We want to make sure it is not prolonged, to the best of our ability. Otherwise, it is going to turn even deadlier, involve more people and I think potentially even make things harder to resolve in Ukraine itself."
