Ukrainian President Volodymyr Zelensky said on Tuesday that rescuers searched under the rubble at a children's hospital for more dead and wounded, on the day Russian missiles hit the facility and cities across the country with a massive barrage during the day. Officials said the number of deaths from the raids rose to 42.

Zelensky added on the social media platform X that 64 people were hospitalized in the capital, in addition to 28 in Kryvyi Rih and six in Dnipro – both in central Ukraine.

This was the most intense Russian shelling of Kyiv in nearly four months and one of the deadliest bombings of the war, as it struck seven of the city's ten districts. The attack on the Okhmadet Children's Hospital, which forced open-heart surgery to halt and young cancer patients to take their treatment outdoors, drew international criticism.

Volodymyr Guviner, the director general of the Okhmadet hospital, said on Tuesday that the 10-story hospital, the largest pediatric medical facility in Ukraine, was caring for about 670 patients at the time of the attack. The missile hit a two-story wing of the hospital.

He told reporters: "The building where we were performing dialysis for children suffering from kidney failure or acute poisoning has been completely destroyed," estimating the total damage to the hospital at $2.5 million.

Danielle Bell, head of the UN team tracking human rights violations in Ukraine, said that at least two people were killed in the hospital and about 50 were injured, including seven children.

She added that the number of casualties would have been much higher had patients not been transferred to a shelter when the sirens first sounded.

Guviner said that authorities are working to restore electricity and water supplies to the hospital.

Kyiv city officials announced Tuesday as a day of official mourning. Entertainment events were banned and flags were flown at half-mast in the capital.

Russia denied responsibility for the attack on the hospital, insisting it does not target civilian sites in Ukraine despite ample evidence to the contrary, including reports from the Associated Press.

Kremlin spokesman Dmitry Peskov reiterated this position on Tuesday, referring to a statement from the Russian Ministry of Defense that blamed a Ukrainian air defense missile for partially destroying the hospital.

Bell, the head of the UN team, dismissed this argument. She stated that an assessment of video footage and on-site findings indicates that the hospital "was directly hit, rather than receiving damage due to an intercepted weapon system."

Bell stated that the hospital may have been struck by a Russian Kh-101 cruise missile. Ukrainian officials said the same thing.

Officials announced that the bodies of three more people were found on Tuesday under the rubble of a residential building in the Shevchenkivskyi district of Kyiv, raising the death toll in that building to ten.

The Russian attack on Monday occurred on the eve of a NATO summit in Washington, where alliance countries are expected to pledge new military and economic support for Ukraine.

Meanwhile, Russian President Vladimir Putin hosted Indian Prime Minister Narendra Modi in Moscow.

New Delhi's importance as a key trade partner has increased since the Kremlin sent troops into Ukraine in February 2022.

Zelensky sharply criticized Modi's visit, saying late on Monday: "It is a great disappointment and a devastating blow to peace efforts to see the leader of the world's largest democracy hugging the most brutal criminal in the world in Moscow on such a day."

Meanwhile, Russian military and regional officials said on Tuesday that Ukrainian drones targeted six Russian regions overnight, in what appears to be a larger-than-usual air attack by Ukrainian forces.

The Russian Ministry of Defense stated that air defense systems in five southern and western Russian regions "destroyed and intercepted" a total of 38 Ukrainian drones.