Officials said that a major Russian missile attack across Ukraine on Monday resulted in the deaths of at least 31 people and injured 154 others, as one of the missiles struck a large children's hospital in the capital city of Kyiv, where emergency crews searched the rubble for victims.

President Volodymyr Zelensky said on social media that the daytime bombardment targeted five Ukrainian cities with more than 40 missiles of various types that hit residential buildings and public infrastructure. The Ukrainian Air Force said it intercepted 30 missiles.

The strikes in Kryvyi Rih, Zelensky's hometown in central Ukraine, resulted in the deaths of 10 people and injuries to 47 in what the city's administration head, Oleksandr Vilkul, described as a massive missile attack. Authorities reported that seven people died in Kyiv.

Zelensky stated on social media: "It is crucial that the world does not remain silent about this now and that everyone sees what Russia is doing."

Western leaders who have supported Ukraine will hold a three-day NATO summit in Washington starting Tuesday to consider how to reassure Kyiv about the alliance’s steadfast support and give hope to Ukrainians that their country can overcome the largest conflict in Europe since World War II.

Zelensky, during a visit to Poland, expressed hope that the summit would provide more air defense systems for Ukraine.

At the Okhmatdyt Children's Hospital in Kyiv, rescue workers searched for victims beneath the rubble of a partially collapsed two-story wing of the facility. The city's mayor, Vitali Klitschko, reported that at least 16 people, seven of whom were children, were injured.

In the main 10-story hospital building, windows and doors were smashed and walls were blackened. Blood was scattered on the floor in one of the rooms. Officials reported that the intensive care unit, operating rooms, and oncology departments were all damaged.

Rescue workers searched for children and medical staff beneath the rubble, and volunteers formed a line, passing bricks and other debris between them. Smoke continued to rise from the building, and volunteers and emergency crews worked in protective masks.

The attack forced the hospital to evacuate and temporarily close. Some mothers carried their children on their backs, while others waited in the yard with their kids as doctors' phone calls rang unanswered.

Just a few hours after the initial strike, air raid sirens sent many to the hospital's shelter. Mothers carried their bandaged children in their arms, while medical staff transported them on stretchers. Volunteers distributed candy to try to calm the children.

Marina Bluskonos said her four-year-old son had undergone spine surgery on Friday.

She burst into tears, saying: "My child is terrified. This should not happen; it is a children's hospital."

The Ukrainian Security Service reported finding debris from a Russian Kh-101 cruise missile at the site and opened proceedings over war crimes charges. The Kh-101 is an air-launched missile that flies low to avoid radar detection. Ukraine said it shot down 11 of 13 Kh-101 missiles fired on Monday.

Czech President Petr Pavel called the attack on the hospital "unjustified" and said he expected to see a consensus at the NATO summit that Russia "poses the biggest threat that we must be fully prepared for."

UN humanitarian coordinator for Ukraine Denise Brown said that attacking children "is unacceptable."

She added in a statement, "Under international humanitarian law, hospitals enjoy special protection."

The Russian defense ministry stated that the strikes targeted Ukrainian defense factories and military air bases and were successful. It denied targeting any civilian facilities and claimed, without evidence, that images from Kyiv indicated that the damage was caused by a Ukrainian air defense missile.

Since the start of the war, which has entered its third year, Russian officials have regularly claimed that Moscow's forces have never attacked civilian infrastructure in Ukraine, despite what officials in Kyiv and reports from the Associated Press assert.

Colonel Yurii Ihnat of the Ukrainian Air Force said Russia is improving the effectiveness of its air strikes, equipping its missiles with enhancements including so-called thermal decoys that confuse air defense systems.

In comments sent to the Associated Press, he said the cruise missiles flew in low during Monday's attack—at altitudes of up to 50 meters (160 feet) from the ground—making them more difficult to hit.

Elsewhere in Kyiv, where seven of the city’s ten districts experienced the heaviest Russian bombardment of the capital in nearly four months, the strikes killed seven people and injured 25, officials said.

About three hours after the initial strikes, additional missiles hit Kyiv, partially destroying a private medical center. The Ukrainian emergency service reported that four people died there.

In the Shevchenkivskyi district of the capital, a section of a three-story residential building was destroyed. Emergency crews searched for victims, and Associated Press reporters saw them remove three bodies.

Resident Halyna Sichevka said the blast wave burned nearby buildings, shattered windows, and tossed a dog into a neighboring yard.

The 28-year-old man said, "Now we have nothing in our apartment—no windows, no doors, nothing. Absolutely nothing."

The Ukrainian Air Force stated that the Kinzhal hypersonic missiles used in the attack are among the most advanced Russian weapons, flying at speeds up to ten times the speed of sound, making them difficult to intercept.

Buildings across the city shook from the explosions. Energy company DTEK reported that three substations were damaged or destroyed in two areas of Kyiv.