KYIV/MOSCOW – Authorities said on Tuesday that one person was killed and 20 others were injured in reported Russian strikes on Kyiv early Tuesday, as multiple explosions rocked the Ukrainian capital.

Kyiv Mayor Vitali Klitschko urged residents to remain in shelters while air defense systems responded to the attack.

Klitschko also said that a fire broke out in a 24-story residential building after it was struck by what was believed to be a missile.

New conflicts

Russian President Vladimir Putin said at a meeting convened to probe the terrorist attack in Starobelsk on Monday that Kyiv's leadership, through deliberate crimes against children in Starobelsk and Genichesk, has itself opted to fundamentally alter the nature of the entire conflict.

Referring to two recent drone attacks targeting children and teenagers at a college in Starobelsk and a residential building in Genichesk, Putin said the Kyiv leadership has decided to "open a new chapter in its series of crimes" and give the conflict as a whole "a new dimension," adding that it was "their choice."

READ MORE: Russia's Rosatom says Ukrainian drone struck Zaporizhzhia nuclear plant

On May 22, a large-scale Ukrainian drone assault hit the campus of Starobelsk College, affiliated with Luhansk Pedagogical University, causing the collapse of a student dormitory building. Eighty-six students were inside the building at the time of the strike. The attack left more than 60 civilians harmed, with 21 fatalities.

On the evening of May 31, Ukrainian drones struck a residential apartment building in Genichesk. A child was killed while 11 others were injured.