Deadly strikes hit residential buildings in Ukraine and a Russian border region Tuesday as an escalation of aerial attacks also wounded dozens and prompted Kyiv to urge speedier Western weapons shipments.
The bombardment of Kyiv and northeastern Kharkiv came less than 24 hours after Russian President Vladimir Putin vowed to step up strikes following an unprecedented Ukrainian attack on the Russian city of Belgorod.
A fresh Ukrainian strike on Russia's border Belgorod region killed at least one person Tuesday and wounded five, the local governor said.
Moscow claimed to have struck only targeted military installations, but Ukraine's Defence Minister Rustem Umerov said Russia is deliberately hitting critical infrastructure and residential neighbourhoods.
Kyiv urged Western allies to respond to the bombardment by speeding up the delivery of air defences, combat drones and long-range missiles at a time when allied backing has wavered.
In Tuesday's attack, Kyiv said Moscow fired 99 missiles but 72 were downed, while Russia said it had shot down nine Ukrainian-fire missiles over the Belgorod border region.
Firefighters and rescue workers were on the scene in Kyiv, with smoke billowing from one of the buildings.
"It's a residential building. They hit a residential building," said Violetta Solovyova, 56.
Galyna Solovyova, 79, suffered a head wound in the strike but was left without a home.
"It's a real horror to be left without... everything. And we don't know about the neighbours. They're people we know. How are they?" she asked, her head bandaged.
Two people were killed and 49 injured in the capital, said Kyiv mayor Vitaly Klitschko.
Ukraine's interior minister Igor Klymenko said two people were killed in the Kyiv region.
National energy company Ukrenergo said 250,000 consumers were without electricity in Kyiv and surrounding areas after the strikes. Temperatures in the region were hovering around three degrees Celsius (37.4 degrees Fahrenheit).
Strikes in Kharkiv killed one person and wounded over 40, as well as damaging multi-storey buildings, said the head of the city's military administration, Oleg Sinegubov.
In a sign of growing concern, Poland on Tuesday scrambled four F-16 fighter jets to its border with Ukraine to protect its airspace.
Poland -- a NATO and EU member -- is a staunch ally of Ukraine as the Russian invasion nears its second anniversary.
During the last wave of deadly attacks on Ukraine on Friday, Poland said a Russian missile had passed through its airspace.
Tuesday's attacks came after an escalation in the war in recent days.
Putin on Monday called an unprecedented Ukrainian attack on the Russian city of Belgorod a "terrorist act" and vowed retaliation.
Moscow also attacked Ukraine with a barrage of drones on New Year's Eve.
Ukraine is seeking assurances from its backers that military aid will continue as any new budget for support is stalled in Washington.
- 'Critical we support Ukraine' -
"Putin is ringing in 2024 by launching missiles at Kyiv and around the country as millions of Ukrainians take shelter in freezing temps. Loud explosions in Kyiv this morning," US Ambassador to Ukraine Bridget Brink wrote on X.
"It's urgent and critical that we support Ukraine now -- to stop Putin here."
Kyiv mayor Klitschko reported multiple explosions and debris from downed missiles hitting the capital as residents were advised to stay in underground shelters.
In the Pechersk district, debris hit the roof of a nine-storey building and another building, the military administration said.
Fires also broke out in a supermarket and a warehouse measuring 2,000 square metres, the mayor said.
"As soon as the security situation allows it, we will definitely restore electricity to everyone," the city's military administration said.
In the city's Podil district, main water pipes have been damaged, it added.
The attacks came after Russia on December 29 launched a wave of strikes across Ukrainian cities, including Kyiv, which killed 39 people.
Moscow also hit Ukrainian cities on New Year's Eve, with Kyiv saying it had foiled a "record" number of drones launched by Russia.