Ukraine condemned on Sunday a Russian airstrike that killed 60 people in a school located in the east of the country, whose basement was used by dozens of people as a shelter.

"In the village of Bilohorivka in the Luhansk region, a Russian bomb killed 60 civilians," Ukrainian President Volodymyr Zelensky said during a video-conference speech at a Group of Seven (G7) summit, AFP news agency reported.

"They were trying to take shelter in an ordinary school building that was targeted by Russian aerial bombardment," he added.

The Ukrainian governor of the Luhansk region, Sergei Gaidai, explained that the impact of a Russian bomb caused a fire in the school in the village of Bilohorivka. Around "60 people died under the rubble," and 27 others were rescued alive, the news agency continued.

The Russian invasion of Ukraine has left thousands dead and millions of refugees, making it the largest European conflict since World War II.

A day before the annual parade in Moscow to celebrate the victory of the Soviet Union against the Nazis, which in Russia is commemorated on May 9, Russian forces sought to complete the capture of the besieged city of Mariupol.

All women, children, and elderly refugees at the Azovstal steel mill were evacuated on Saturday in a multi-day operation carried out by the U.N. and the Red Cross in coordination with Russia and Ukraine.

"Surrender is not an option because Russia is not interested in our lives," said Ilya Somoilenko, intelligence officer of the Azov Battalion, the Ukrainian military unit resisting at the plant, at a press conference broadcast by video, according to Telam.

Following the evacuation of civilians, Zelensky said on Saturday night that Ukraine would attempt to remove the wounded and medical personnel from the site.

He added that there would be further efforts would continue to open more safe humanitarian corridors to evacuate civilians still remaining in other parts of Mariupol and neighboring localities.