Russian missiles and rockets have hit the the cultural heart of Ukraine’s second city in what officials said was a deadly and “barbaric” attack.
An opera house, concert hall and government offices were hit in Freedom Square, in the centre of the north-eastern city, Kharkiv.
At least 20 people, including a child were injured, but authorities are still trying to clarify if anyone was killed.
The attack came as Ukraine’s president said Russia was committing war crimes.
“Russian forces have today cruelly targeted Kharkiv with artillery fire,” Mr Zelensky said. “This is a peaceful place, peaceful suburbs… The Russians knew where they were shooting…,” he said.
Video footage showed a missile hitting the local government building and exploding, causing a massive fireball.
Kharkiv has been bombed heavily for days now. Ukraine’s government accuses Russia of trying to lay siege to Kharkiv and other cities, including the capital Kyiv, where a huge Russian armoured convoy is approaching.
Ukraine’s Foreign Minister Dmytro Kuleba said the world must do more to punish Russia for the “barbaric” attack on Freedom Square and residential neighbourhoods, accusing the Russian President Vladimir Putin of committing “more war crimes out of fury, murders innocent civilians”.
The sixth day of Russia’s invasion of Ukraine has seen continued attacks on several fronts, but the Russian advance has reportedly been slowed by Ukrainian resistance.
People in the southern city of Kherson say it is now surrounded, and the mayor of Mariupol, a port city also in the south of Ukraine said it had been fired upon overnight.
Meanwhile new satellite images showed a 40-mile (64km) long Russian military convoy snaking its way toward the capital, Kyiv, where air raid sirens were again ringing out on Tuesday morning.
The convoy – which has appeared to slow in the last 24 hours – includes armoured vehicles, tanks, artillery and logistical vehicles, and is said to be less than 18 miles (30km) from Kyiv.
Kherson surrounded
The mayor of Kherson said Russian forces had set up checkpoints surrounding the city, which has a population of some 300,000 people, and is located in the south, near to Moscow-controlled Crimea.
But Mayor Igor Kolykhayev said defiantly on Facebook that the city “has been and will stay Ukrainian”.
A journalist in the city, Alena Panina told broadcaster Ukraine 24 that “the city is actually surrounded, there are a lot of Russian soldiers and military equipment on all sides, they set up checkpoints at the exits.”
There was still electricity, water, and heating in Kherson but said it was getting difficult to bring food into the city because it is stored in warehouses on Kherson’s outskirts, she added.
Mariupol
Also in the south, there were strong words from the mayor of the strategically located port city of Mariupol, who said the city had been under constant shelling.
“Russian Nazis seek the genocide of the Ukrainian nation,” Vadym Boychenko told Ukrainian 24 News. “We will fight until the last bullet… If they run out, we will use our teeth against the enemy that is moving towards Mariupol.”
Russian-backed separatist leader, Denis Pushilin, has said his forces will aim to encircle Mariupol on Tuesday, the Russian state-owned RIA Novosti news agency reported.
Investigation into war crimes
Claims that Russia is committing war crimes are mounting, with Ukraine’s president, local government officials, and Amnesty International saying the attacks on residential districts need to be investigated.
“A state that commits war crimes against civilians can’t be a member of the UN Security Council,” Mr Zelensky said, referring to the end of Russia’s month-long term as the UN Security Council’s president.
Russia has previously denied targeting residential areas, but the International Criminal Court (ICC) – which examines war crimes – is looking to open an investigation.
Chief prosecutor Karim Khan still needs the approval of ICC judges to begin work, but for now has asked his team to start collecting evidence of abuses, such as attacks on civilians.
Mr Khan said his investigation would look into alleged crimes arising from the fighting, as well as violations dating back to the initial Russian invasion in 2014. However any Russian nationals accused of committing war crimes, crimes against humanity or genocide in Ukraine, would have to be extradited by the Kremlin before standing trial in The Hague.
More than half a million people across Ukraine have fled their homes to escape the fighting, according to the United Nations, and more than 130 civilians have been killed in Ukraine since Thursday, including 13 children.
On Monday, envoys for Russia and Ukraine held talks at the Belarus border on Monday, but they reached no agreements other than a commitment to meet again in the next few days.
Mr Zelensky has also called for the West to consider a no-fly zone over Ukraine – something Washington has so far ruled out over fears it could draw the US into a direct conflict with Russia.