Russia blasted the main children's hospital in Kyiv with a missile in broad daylight on Monday and rained missiles down on other cities across Ukraine, killing at least 41 civilians in the deadliest wave of air strikes for months

Parents holding babies walked in the street outside the hospital, dazed and sobbing after the rare daylight aerial attack. Windows had been smashed and panels ripped off, and hundreds of Kyiv residents were helping to clear debris.

"It was scary. I couldn't breathe, I was trying to cover (my baby). I was trying to cover him with this cloth so that he could breathe," Svitlana Kravchenko, 33, told Reuters.

President Volodymyr Zelenskiy, who stopped in Poland before heading off to Washington for a NATO summit, put the death toll at 37, including three children. More than 170 were injured.

But tallies of casualties from the sites of attacks in different regions totalled at least 41.

Writing on the Telegram messaging app, Zelenskiy said more than 100 buildings had been damaged, including the children's hospital and a maternity centre in Kyiv, children's nurseries and a business centre and homes.

"The Russian terrorists must answer for this," he wrote. "Being concerned does not stop terror. Condolences are not a weapon."

The Interior Ministry said there had also been damage in the central cities of Kryvyi Rih and Dnipro and two eastern cities.

The government proclaimed a day of mourning on Tuesday for one of the worst air attacks of the war, which it said demonstrated that Ukraine urgently needed an upgrade of its air defences from its Western allies.

Air defences shot down 30 of 38 missiles, the air force said.

An online video obtained by Reuters showed a missile falling towards the children's hospital followed by a large explosion. The location of the video was verified from visible landmarks.

The Security Service of Ukraine identified the missile as an Kh-101 cruise missile.

Kyiv's military authorities said 27 people had died in the capital, including three children, and 82 were wounded in the main missile volley and a strike that came two hours later.

(With Inputs From International Agencies)