At least 17 people were injured in the attack in the besieged port city in the south of the country, including women who were in labour and young children, the deputy mayor of the city said.
Video footage from the hospital shows bloodied pregnant women being carried away on stretchers, while in the grounds there is a huge crater estimated to be around 20ft deep and 30ft wide.
The governor of Donetsk claimed that the airstrike happened during an agreed ceasefire period to allow civilians to flee to safety.
It is understood that most of the victims were in a bomb shelter and the deputy mayor said he is “absolutely sure” that Russian troops knew they were bombing a maternity hospital.
Sergei Orlov told the Today programme on BBC4: “I am absolutely sure that they know about this facility.
“This is the third hospital that they have destroyed in the city. The previous day they destroyed hospital number nine by artillery shelling. This was a Covid hospital with 300 beds.
“They have also attacked and destroyed a blood collection station in Mariupol. So, it is the third hospital. I’m absolutely sure they know what are their targets.”
President Zelensky has branded the attack a “war crime” and reiterated his call to the West to impose a no-fly zone.
He posted footage of the damage online from what he said was a “direct strike” on the hospital and said that children were among people “under the wreckage”.
In a tweet, he said: “People, children are under the wreckage. Atrocity!”
“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.”
Boris Johnson has condemned the airstrike as “depraved” and vowed to step up support to the Ukrainian military, and to impose the “maximum economic cost” on Russia.
What did Volodymyr Zelensky say?
In a video message, President Zelensky condemned the attack on the hospital in Mariupol. He said:
“Europeans, Ukrainians, Mariupol residents. Today is the day that defines everything. Defines who is on whose side.
“Russian bombs fell on a hospital and maternity hospital in Mariupol. Children’s hospital. Maternity hospital that is functioning. Buildings are destroyed.
“As of now, there are 17 wounded. Disassembly of the debris is still ongoing.
“People began to hide from the air threat in time. From 500kg aviation bombs dropped by the invaders on Ukrainian cities. Many times already.
“Children’s hospital. Maternity hospital. What did they threaten the Russian Federation with? What kind of country is this - the Russian Federation which is afraid of hospitals and maternity hospitals and destroys them?
“Were there little Banderivtsi? Or were pregnant women going to fire at Rostov? Did someone in the maternity hospital abuse Russian speakers?
“What was that? Was it the denazification of the hospital? It is beyond atrocities already.
“Everything that the invaders are doing to Mariupol is beyond atrocities already.
“Europeans. Ukrainians. Mariupol residents. Today we must be united in condemning this war crime of Russia, which reflects all the evil that the invaders brought to our land. All destroyed cities.
“What they did to Volnovakha, Kharkiv, Izyum, Okytyrka, Chernihiv, Borodyanka, Hostomel, Zhytomyr, and dozens of other Ukrainian cities which never posed any threat to the Russian Federation.
“Destroyed hospitals, destroyed schools, churches, houses. And all the people killed. All the children killed.
“The air bomb on the maternity hospital is the final proof. Proof that the genocide of Ukrainians is taking place.
“Europeans. You won’t be able to say that you didn’t see what happened to Ukrainians, what happened to Mariupol residents. You saw, you know.
“Therefore, you must increase sanctions against Russia so that it no longer has any opportunity to continue this genocide.
“You must put pressure on Russia to force it to sit down at the negotiating table and end this brutal war.
“Moscow knows very well that Mariupol is also the Donetsk region. We have heard so much from Russia about the inhabitants of the Donetsk region.
“So many accusations, so many demands. And now we see how Russia actually treats the residents of the Donetsk region, treats ordinary people who live in the houses of Mariupol, work at the enterprises of the city of Mariupol, are treated in hospitals of Mariupol and give birth to children.
“Imagine, people like you give birth to children in the maternity hospitals of Mariupol.
“We have not done and never would have done anything similar to this war crime to any of the cities of the Donetsk, Luhansk or any other region. To any of the cities on earth. Because we are people.”
Support people fleeing the devastating conflict in Ukraine: donate to the DEC appeal
Disasters Emergency Committee (DEC) charities and their local partners are in Ukraine and in neighbouring countries providing food, water, shelter and medical assistance. Learn more and donate what you can today
A message from the editor:
Thank you for reading. NationalWorld is a new national news brand, produced by a team of journalists, editors, video producers and designers who live and work across the UK. Find out more about who’s who in the team, and our editorial values. We want to start a community among our readers, so please follow us on Facebook, Twitter and Instagram, and keep the conversation going. You can also sign up to our newsletters and get a curated selection of our best reads to your inbox every day.