Eighteen adults and two children were hospitalized, while the rest received medical treatment on the site, Klitschko said on Telegram.
A children's hospital, an apartment building, private houses, and cars were damaged by the airstrike in eastern Dniprovskyi and southeastern Darnytskyi districts, Klitschko said.
The Ukrainian Air Force said in a statement that it had intercepted all 10 ballistic missiles fired against Kiev.
The air strike marked the second attack on the Ukrainian capital this week.
(With UNI inputs)