KYIV — A major Russian missile attack across Ukraine on Monday killed at least 31 people and injured 154, officials said, with one striking a large children’s hospital in the capital of Kyiv, where emergency crews searched the rubble for victims.

The daytime barrage targeted five Ukrainian cities with more than 40 missiles of different types hitting apartment buildings and public infrastructure, President Zelensky said on social media. Ukraine’s air force said it intercepted 30 missiles.

Strikes at Kryvyi Rih, Zelensky’s birthplace in central Ukraine, killed 10 people and injured 47 in what the head of city administration, Oleksandr Vilkul, said was a massive missile attack. Seven people were killed in Kyiv, authorities said.

“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,” Mr. Zelensky said on social media.

Western leaders who have backed Ukraine will hold a three-day NATO summit in Washington beginning Tuesday to look at how they can reassure Kyiv of the alliance’s unwavering support and offer Ukrainians hope that their country can come through Europe’s biggest conflict since World War II.

Zelensky said during a visit to Poland he hopes the summit will provide more air defense systems for Ukraine.

At the Okhmatdyt children’s hospital in Kyiv, rescuers searched for victims under the rubble of a partially collapsed, two-story wing of the facility. Mayor Vitali Klitschko said at least 16 people, seven of them children, were injured.

On the hospital’s main 10-story building, windows and doors were blown out and walls were blackened. Blood spattered the floor in one room. The intensive care unit, operating theaters and oncology departments all were damaged, officials said.

Rescuers searched for children and medical workers in the rubble. Volunteers formed a line, passing bricks and other debris to each other. Smoke still rose from the building, and volunteers and emergency crews worked in protective masks.

The attack forced the evacuation of the hospital and its temporary closure. Some mothers carried their children away on their backs, while others waited in the courtyard with their children as calls to doctors’ phones rang unanswered.

A few hours after the initial strike, another air raid siren sent many of them hurrying to the hospital’s shelter. Led by a flashlight through the shelter’s dark corridors, mothers carried their bandaged children in their arms and medical workers carried them on gurneys. Volunteers handed out candy to try to calm the children.

Marina Ploskonos said her 4-year-old son had spinal surgery Friday.

“My child is terrified,” she said. “This shouldn’t be happening, it’s a children’s hospital,” she said, bursting into tears.

Ukraine’s Security Service said it found wreckage from a Russian Kh-101 cruise missile at the site and had opened proceedings on war crime charges. The Kh-101 is an air-launched missile that flies low to avoid detection by radar. Ukraine said it shot down 11 of 13 Kh-101 missiles launched Monday.

The Czech president, Petr Pavel, said the hospital attack was “inexcusable” and that he expected to see at the NATO summit a consensus that Russia was “the biggest threat for which we must be thoroughly prepared.”

The United Nations’ humanitarian coordinator for Ukraine, Denise Brown, said striking children was “unconscionable.”

“Under international humanitarian law, hospitals have special protection,” she said in a statement.

Russia’s Defense Ministry said the strikes targeted Ukrainian defense plants and military air bases and were successful.

It denied aiming at any civilian facilities and claimed without evidence that pictures from Kyiv indicated the damage was caused by a Ukrainian air defense missile.