A "Russian" barrage of missiles pounded apartment buildings and other targets in the city of Zaporizhzhia on Sunday, killing at least 17 people and wounding scores more, according to Ukrainian officials.
The blasts in the Ukraine-controlled city left at least one high-rise apartment building partially collapsed.
Some 20 private homes and 50 apartment buildings were also damaged.
At least 49 people were hospitalised, including six children, while dozens more were treated for moderate to light injuries.
Sunday's attack came one day after an explosion on a key bridge linking the Crimean Peninsula with Russia, which caused part of it to fall into the sea.
While Russia targeted Zaporizhzhia before the blast, the attack was a significant blow to Moscow's prestige in the Black Sea region and damaged a key supply line for its troops in southern Ukraine.
Russian war bloggers called for retaliation against Ukraine after the explosion, though Kyiv has not claimed responsibility.
Ukrainian President Zelenskyy called the bombing on Sunday "merciless".
"Absolute evil," he said. "Savages and terrorists. From the one who gave this order to everyone who fulfilled this order. They will bear responsibility."
In recent weeks, Moscow has repeatedly struck the southern Ukrainian city, which sits within a disputed region Russian President Vladimir Putin annexed in violation of international law last week.
At least 19 people died in a suspected Russian missile strike on residential areas in Zaporizhzhia on Thursday.
Local residents Tetyana Lazun’ko, 73, and her husband, Oleksii, were caught up in the bombardment this weekend.
They took shelter in the hallway of their top-floor apartment, after hearing warning sirens, but were spared the worst of the blast, which left them in a state of shock.
“There was an explosion. Everything was shaking,” Lazun’ko told AP. “Everything was flying and I was screaming.”
Their apartment, which the pair have lived in since 1974, was left covered in debris and broken glass.
“Why are they bombing us? Why?” Lazun’ko added.
Part of the Zaporizhzhia region currently under Russian control is home to Europe’s largest nuclear power station.
Fighting has repeatedly imperilled the Zaporizhzhia Nuclear Power Plant, with Ukrainian authorities shutting down its last operating reactor last month to prevent a possible radiation disaster.
The International Atomic Energy Agency (IAEA) said Saturday that the plant has since lost its last remaining external power source as a result of renewed shelling and is now relying on emergency diesel generators.
Russia and Ukraine trade blame over who is behind the shelling.