The strike was one of the deadliest on Kyiv since Russia launched its full-scale invasion in February 2022, and came as direct peace talks between the two sides appeared to stall.

Zelensky said "an entire section of an apartment block" was destroyed and rescuers were searching under the rubble for possible survivors.

AFP journalists heard drones flying over the city and explosions ringing out as Ukrainian air defense systems attempted to intercept the barrage.

Dozens of residents took shelter in a metro station in central Kyiv, sleeping on mats, exchanging information on the drone and missile threat or reassuring pets, AFP journalists saw.

Residents in Kyiv told AFP the attack was one of the strongest in recent memory.

"It was probably the most hellish night in my memory for our neighborhood," 20-year-old Ukrainian student Alina Shtompel told AFP.

"It is indescribably painful that our people are going through this right now."

Some 27 locations in Kyiv were hit, Interior Minister Igor Klymenko said.

One person was also killed and 10 wounded in a strike on the southern port city of Odesa, while attacks on the Sumy and Kherson regions later in the day killed two others, authorities said.

A total of 440 drones and 32 missiles were used in the strikes nationwide, Zelensky said.

"Kyiv has faced one of the most horrific attacks," the Ukrainian leader wrote on Facebook.

"Right now in Kyiv, efforts are underway to rescue people from under the rubble of an ordinary residential building -- it's still unclear how many remain trapped."

He urged the international community not to "turn a blind eye".

Russian President Vladimir "Putin does this solely because he can afford to continue the war. He wants the war to go on," he said.

Another Kyiv resident, Sergiy, said his windows were shattered during the strikes.

"I was asleep. There was a loud bang. The window was smashed, and glass rained down on me," he said.

Residential buildings, educational institutions and "critical infrastructure facilities" were all hit, Interior Minister Igor Klymenko wrote on Telegram.

A total of 114 were wounded in the attack on Kyiv, 68 of them hospitalized, Mayor Vitaliy Klitschko said.

He reported earlier that a US citizen had died in a Russian attack on the capital's Solomyansky district.

"During the attack on Kyiv... a 62-year-old US citizen died in a house opposite to the place where medics were providing assistance to the injured," Klitschko said on Telegram.

Zelensky's chief of staff, Andriy Yermak, said the new strikes showed Moscow was "continuing its war against civilians".

More than three years into its full-scale invasion of Ukraine, Moscow has kept up its attacks despite efforts by the United States to broker a ceasefire.

Talks have stalled. Moscow has rejected the "unconditional" truce demanded by Kyiv and its European allies, while Ukraine has dismissed Russia's demands as "ultimatums".

Zelensky had been hoping to speak with his US counterpart Donald Trump on the sidelines of the G7 summit in Canada, but the US leader cut short his visit, amid the escalating conflict between Israel and Iran.