Multiple rounds of loud explosions were heard in the Ukrainian capital throughout the early hours of the morning, AFP journalists reported, as residents took shelter in underground stations.

Daytime scenes across the capital showed rescue workers extinguishing fires and sifting through debris of heavily damaged buildings -- houses, shopping centres, museums, theatres, schools and universities.

Russian President Vladimir Putin had earlier threatened retaliation for Ukrainian strikes in Russian-occupied eastern Ukraine that killed 21 people in a vocational school.

Sofia Melnychenko, 21, thought she was safe in the subway, "but then there were three loud explosions, and after the fourth one the ceiling in the metro started crumbling," she told AFP.

"There was complete chaos. Children started screaming, people were panicking," she added.

"It was a very frightening night."

The Ukrainian air force said the raid involved 600 drones and 90 missiles, of which 549 drones and 55 missiles were intercepted.

- 'Genuinely deranged' -

Kyiv has been grappling with an acute air defence missile deficit since the US-Israeli air campaign against Iran drove up demand for US-made Patriot rounds.

European leaders reacted by saying the salvo showed Russia's desperation.

"Terror against civilians is not strength. It's despair," EU chief Ursula von der Leyen said on X.

French President Emmanuel Macron said the strikes signalled "the dead end of Russia's war of aggression", while German Chancellor Friedrich Merz called the use of Oreshnik a "reckless escalation".

Ukrainian President Volodymyr Zelensky, on Telegram, called Russia "genuinely deranged".

"Three Russian missiles against a water supply facility, a market burnt down, dozens of residential buildings damaged, several ordinary schools, and he launched his 'Oreshnik' against Bila Tserkva (southwest of Kyiv)," he said, referring to the Russian president.

Russia's army confirmed it had launched the Oreshnik at Ukraine for the third time in the war, saying it was "in response to Ukraine's terrorist attacks on civilian infrastructure on Russian territory".

Moscow denied targeting civilians, saying it had struck command posts of the Ukrainian army and intelligence.

Kyiv Mayor Vitali Klitschko said two people had been killed in the capital and dozens wounded, while the head of the surrounding Kyiv region said two people had also been killed there.

Klitschko said damage had been recorded in every district of Kyiv, with strikes causing fires at schools and wreaking havoc on popular markets, malls and museums.

The residence of the Albanian ambassador was also hit and the Balkan country summoned the Russian envoy in protest.

Buildings housing a studio of German broadcaster ARD and an office for German outlet DW were damaged as well, the outlets said in statements. Both premises were empty of people at the time.

Ukrainian authorities said Russian strikes had also wounded 12 people in the Kharkiv region, 11 in the Cherkasy region and seven in the Dnipropetrovsk region.

- Retaliation -

Ukraine had been expecting a major attack after its own forces launched a drone barrage on Starobilsk, in the Russian-occupied east of the country, which Moscow said hit a college dormitory and killed 21 people, most of them young female students.

Launched overnight on Thursday to Friday, the drone salvo -- one of Ukraine's deadliest such strikes in months -- also wounded dozens in the city, located in the occupied Lugansk region.

Ukraine denied targeting civilians, saying it had hit a Russian drone unit stationed in the area.

Russia's foreign ministry had said on Friday those responsible would face "inevitable and severe punishment".

Ukraine regularly targets Russian-controlled areas of the country with drones, arguing that the strikes are retaliation for Russian attacks.

Kyiv has recently expanded its drone capabilities and stepped up strikes on internationally recognised Russian territory, including residential areas and oil export infrastructure.

Moscow has hit Ukraine almost daily with barrages of missiles and drones since launching its full-scale invasion of the country in 2022, also hitting infrastructure and causing civilian deaths. It denies targeting civilians.

US-led efforts to negotiate an end to more than four years of war have slowed in recent months, with Washington's attention diverted towards its conflict in the Middle East.