Evacuations resumed on Saturday from Kramatorsk, in eastern Ukraine, where a missile strike killed 52 people at a railway station, as British Prime Minister Boris Johnson became the latest Western leader to visit Kyiv and Ukrainians were urged to flee a feared Russian offensive before it was too late.
Hailing the country's response to the Russian invasion, Johnson offered Ukraine armoured vehicles and anti-ship missiles.
"It is because of President (Volodymyr) Zelensky's resolute leadership and the invincible heroism and courage of the Ukrainian people that (Vladimir) Putin's monstrous aims are being thwarted," he said after meeting Zelensky.
Johnson, who a day earlier pledged to send Ukraine "high-grade military equipment" including Starstreak anti-aircraft missiles and 800 anti-tank missiles, added that the discovery of civilian bodies in Ukrainian towns had "permanently polluted" Russian President Vladimir Putin's reputation.
Former Italian Prime Minister Silvio Berlusconi, meanwhile, said he was "deeply disappointed" and pained by his friend Putin's attack on Ukraine.
Six weeks into Russia's invasion, Moscow has shifted its focus to eastern and southern Ukraine after stiff resistance thwarted plans to swiftly capture Kyiv.
EU leaders were meeting with President Zelensky on Friday as news emerged of the devastating attack on Kramatorsk's station. The 52 victims included five children.
With thousands killed in the fighting and more than 11 million fleeing their homes or the country, Zelensky called on the West to follow the UK's example on military aid.
US President Joe Biden on Friday accused Russia of being behind a "horrific atrocity" in the de facto capital of the Ukrainian-controlled Donetsk region, and France condemned the strike as a "crime against humanity".
Moscow denied responsibility for the rocket attack on Friday morning, which also wounded 109 people, according to the latest official count.
With the conflict moving away from areas first occupied by Russian forces after the February 24 invasion, the mayor of eastern Lysychansk Oleksandr Zaika called on the city's residents to evacuate as soon as possible due to constant shelling by the Russian army.
"I ask you to evacuate. It has become very difficult in the city, enemy shells are already flying into different places," Zaika said in a video message.
Stressing that "no one is going to give up the Luhansk region", he added that there were stocks of humanitarian aid in the city "but that doesn't mean it will save your life if an enemy shell arrives".
Minibuses assembled at a church in Kramatorsk to collect shaken evacuees on Saturday. Almost 80 people, most of them elderly, took shelter overnight in a building, not far from the targeted station.
"There were around 300 to 400 people who rushed here after the strike," Yevgeny, a member of the Protestant church, told AFP.
"They were traumatised. Half of them ran to shelter in the cellar, others wanted to leave as soon as possible. Some were evacuated by bus in the afternoon (on Friday)."
The station in Kramatorsk was being used as the main evacuation hub for refugees from the parts of the eastern Donbas region still under Ukrainian control.
AFP reporters at the station saw the remains of the missile tagged in white paint with the words "for our children" in Russian. The expression is frequently used by pro-Russian separatists in reference to their losses since the start of the first Donbas war in 2014.
The governor of Donetsk claimed a missile with cluster munitions was used in the attack, according to remarks published by the Interfax news agency.
The strike came as European Commission President Ursula von der Leyen and EU foreign policy chief Josep Borrell were in Kyiv for talks with Zelensky and to visit the scene of civilian killings in Bucha.
Russia faced "decay" because of ever tougher sanctions and Ukraine had a "European future", von der Leyen said at a news conference with Zelensky on Friday.
"My instinct says: If this is not a war crime, what is a war crime?" she said of the Bucha killings, calling for a thorough investigation.
Joining the Western solidarity campaign, Austrian Chancellor Karl Nehammer also arrived in Kyiv and on Saturday visited Bucha.
Russian troops appear to be seeking to create a long-sought land link between occupied Crimea and the Moscow-backed separatist territories of Donetsk and Lugansk in the Donbas region.
Ukraine said it had agreed a third prisoner exchange with Russia and that 12 soldiers and 14 civilians would be returning home.
Moscow's defence ministry said Russian forces had destroyed an ammunition depot in the Dnipro region, and struck 85 Ukrainian military targets in the previous 24 hours.
Moscow added that Russian troops had opened fire on a Ukrainian vessel trying to evacuate commanders of the Azov battalion from the besieged city of Mariupol.
Members of the Azov Special Operations Detachment have been fighting Russian forces in southeastern Mariupol located between Russia-occupied Crimea and pro-Russian separatist regions in Ukraine's east.
Bucha -- where authorities say hundreds were killed, some with their hands bound -- has become a byword for the brutality allegedly inflicted under Russian occupation.
But Zelensky has warned that worse is being uncovered.
"They have started sorting through the ruins in Borodianka," northwest of Kyiv, he said on Friday. "It is much more horrific there. There are even more victims of Russian occupiers."
Conflict in the area has wrought massive destruction and bodies are only now being retrieved, with 27 recovered from two destroyed buildings, according to Prosecutor General Iryna Venediktova.
Fresh allegations also emerged from Obukhovychi, northwest of Kyiv, where villagers told AFP they were used as human shields.
Moscow has denied targeting civilians, but growing evidence of atrocities has galvanised Ukraine's allies in the EU, which has approved an embargo on Russian coal and the closure of its ports to Russian vessels.
The bloc has frozen 30 billion euros ($33 billion) in assets from blacklisted Russian and Belarusian individuals and companies, it said Friday.
It also blacklisted Putin's two adult daughters and more than 200 others as part of its latest sanctions package, according to an official list.
The United States and Britain had already sanctioned the Russian leader's daughters.
Borrell has pledged the EU would supply 7.5 million euros to train Ukrainian prosecutors to investigate war crimes allegedly committed by Russia.
Ukraine has welcomed the new pressure on Moscow, but continues to push for harsher sanctions and more heavy weaponry.
Western companies have joined the bid to isolate Russia, US video hosting service YouTube blocking the channel of the Russian lower house of parliament. Russian officials have warned of reprisals.
As sanctions bite, credit rating agency Standard and Poor's Global Ratings downgraded Russia's foreign currency payments rating to "selective default" after Moscow paid a dollar-denominated debt in rubles this week.
