At least seven people have been killed in a Russian missile attack on residential buildings in the eastern Ukrainian town of Pokrovsk, officials say.
Two missiles hit the town – the second as rescuers were searching for victims of the first.
Dozens of people were injured, including police officers and rescuers. Two children were among more than 30 civilians who were hurt.
Rescue efforts are continuing.
Pokrovsk lies about 70km (43 miles) north-west of Donetsk city, which is occupied by Russian forces. Before the war it had a population of around 60,000 people.
Pavlo Krylenko, the head of the Donetsk region, said the first strike killed five civilians, and that an official from the emergency services was killed in the second strike. A person who works in the military also died.
He added that the buildings which were “destroyed and damaged” were “high-rise buildings, private houses, administrative buildings, catering establishments [and] a hotel”.
“Russia is a terrorist state. And she must be punished for her crimes!” he added in a post on Telegram.
According to other Ukrainian officials, the second missile struck 40 minutes after the first, killing and wounding rescuers as they searched for survivors in the ruins of what Mr Zelensky described as an “ordinary residential building”.
He publishing a video of a five-storey building that had its top floor destroyed.
Amid scenes of general chaos and confusion it showed civilians clearing away rubble, and rescuers helping people into ambulances.
Kateryna, a resident who who was injured in the first attack, told the Reuters news agency she was at home when the missile struck.
“The flame filled up my eyes. I fell down on the floor, on the ground. My eyes (hurt) a lot, otherwise I am ok, just the shrapnel in my neck.”
Andriy Yermak, head of Ukraine’s Presidential Office, said at least two civilians were also killed when Russian guided bombs hit “private houses” in the Kharkiv Region on Monday evening.
Five people were injured in those strikes, he said.
We were in Pokrovsk in May reporting on the thousands of people returning there to live close to the front line.
They continue to ignore warnings from local authorities to stay away because of the real risks.
The sights of rescue teams sifting through rubble are a reminder of how enduring those hazards are.
It is a town constantly on a war footing, where civilians mingle with soldiers. Our team have stayed in the Hotel Druzbha and eaten in the mafia-themed Corleone restaurant.
Both are prominent hubs in this eastern community. Both are now gutted from the impact of a Russian missile.
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The attacks came a day after a Russian “guided bomb” hit a blood transfusion centre in north-eastern Ukraine, killing two people, according to Ukrainian officials.
Ukraine has been trying to regain territory occupied by Russia but has made modest gains since launching a counter-offensive two months ago.
On Sunday Mr Zelensky sought to justify attacks on Russian ships in the Black Sea, telling Argentine newspaper La Nacion that Ukraine “has to find another method to end the blockade of our water”.
“If Russia continues to dominate its territory in the Black Sea and blockading, firing missiles, then Ukraine will do the same, which is a fair protection of our chances,” he said.
Russia withdrew from a deal allowing the export of Ukrainian grain and warned ships in the Black Sea they could face military action, prompting Ukraine to issue a similar declaration.
Last week, a Russian tanker with 11 crew members was hit by what Moscow said was a Ukrainian attack in the Black Sea. Although Ukraine did not comment publicly, a security service source told the BBC a sea drone had been used.
That followed a similar sea drone attack on a Russian naval ship near the Russian port of Novorossiysk, which is a major hub for Russian exports.
Naval drones, or sea drones, are small, unmanned vessels which operate on or below the water’s surface. Research by BBC Verify suggests Ukraine has carried out several attacks with sea drones.