According to AP this was the biggest bombardment of Kyiv in several months.

Ukrainian President Volodymyr Zelenskyy said Russia targeted five cities with more than 40 missiles of different types.

"It is very important that the world should not be silent about it now and that everyone should see what Russia is and what it is doing,” Zelenskyy said on social media.

The attack struck Okhmatdyt children's hospital in Kyiv, Ukraine's biggest children's medical facility but the update about casualties from there is not definite yet. The rescuers were searching for people under the rubble of a partially collapsed wing of the facility.

In Kryvyi Rih, 31 people were injured in addition to the 10 deaths in what the head of city administration, Oleksandr Vilkul, said was a massive missile attack. Explosions were also reported by local officials in Ukraine's central Dnipropetrovsk region.

A two-story building at the children's hospital was partly destroyed. On the hospital's main 10-story building, windows and doors were blown out and walls were blackened.

Medical personnel and local people helped shift the rubble as they searched for children and medical workers who could be trapped underneath. Volunteers formed a line, passing stones and debris to each other. Smoke still rose from the building, and volunteers and emergency crews worked in protective masks.

The attack comes on the eve of a three-day NATO summit in Washington, which will look at how to reassure Ukraine of the alliance's unwavering support and offer Ukrainians hope that their country can come through Europe's biggest conflict since World War II.

It was the heaviest Russian bombardment of Kyiv in almost four months. The daylight attacks included Kinzhal hypersonic missiles, one of the most advanced Russian weapons, the Ukrainian air force said. The Kinzhal flies at 10 times the speed of sound, making it hard to intercept. City buildings shook from the blasts. An entire section of a residential multistory building in one district of Kyiv was destroyed, officials said.

The Kyiv city administration reported falling debris, presumably from intercepted missiles, in a handful of Kyiv areas, starting fires. Thick plumes of smoke rose from several Kyiv neighborhoods.

The head of Ukraine's presidential office, Andrii Yermak, said the attack occurred at a time when many people were in the city's streets.

Kyiv Mayor Vitalii Klitschko said official assessments of the attack's consequences were still being carried out.