Zelenskyy’s remarks came in his latest video statement to Ukraine’s citizens, The Associated Press reported.
The remarks coincided with Sunday reports that Russian forces had destroyed an art school building in Mariupol where as many as 400 people were believed to have sought shelter.
No immediate estimates emerged on possible casualties but local officials said about 130 people had been rescued and more could remain under the rubble, the AP reported.
“To do this to a peaceful city, what the occupiers did, is a terror that will be remembered for centures to come,” Zelenskyy said, according to the report.
Previously in Mariupol, a theater being used as a shelter also was bombed – despite the message “Children” in Russian posted outside as a plea for the site to be spared.
Zelenskyy also claimed that Russian fighters weren’t stopping to recover the bodies of their own dead troops in some areas of Ukraine.
“In places where there were especially fierce battles, the bodies of Russian soldiers simply pile up along our line of defense — and no one is collecting these bodies,” he said.
He described a battle near Chornobayivka in the south, where Ukrainian forces held their positions and six times beat back the Russians, who just kept “sending their people to slaughter.”