Ukrainian officials say at least four people have been killed and 10 injured in the latest Russian attacks, a day after Moscow hit Kyiv in the deadliest series of attacks this year.

In the bordering Sumy region, two women, an elderly man and a toddler were killed and three others injured after a Russian drone hit a residential apartment building, Oleh Hryhorov, head of the regional military administration, said on Friday.

In a separate attack, a missile attack on the central city of Kryvyi Rih, in the Dnipropetrovsk region, injured seven people, Oleksandr Vilkul, head of the city’s defence council, said on Telegram.

Two of the injured women remain in hospital, said Vilkul, adding that nine apartment blocks, a school building, a company, several shops, garages and about 10 vehicles were damaged. Two residential buildings were also cut off from the gas supply.

Kryvyi Rih, Ukrainian President Volodymyr Zelenskyy’s hometown and a major industrial centre, has been repeatedly attacked during the war.

The Russian attacks came a night after a huge barrage on the capital Kyiv, whose death toll has risen to at least 30 people, according to authorities.

A day of mourning is being observed in Kyiv on Friday following the deadliest Russian attack on the Ukrainian capital this year.

United Nations Secretary-General Antonio Guterres condemned Russia’s barrage and repeated a ceasefire call.

“Attacks against civilians and civilian infrastructure wherever they occur are a clear violation of international humanitarian law and must stop immediately,” said his spokesman Stephane Dujarric.

But the Kremlin pledged to further ramp up “pressure” on Kyiv, sticking to its no-compromise rhetoric.

Ukraine’s air force said it had shot down 476 of the 496 drones and 48 of the 74 missiles, including hard-to-intercept ballistic projectiles, which Russia had launched.

The European Union’s top diplomat Kaja Kallas said she would propose new sanctions on Moscow over the attack.

Zelenskyy said his forces would “definitely” retaliate for the Wednesday-to-Thursday overnight attack, adding that Russian President Vladimir Putin had “been preparing this massive strike against Ukraine for some time now”.

Ukrainian attacks on Russia

At least two people were killed overnight into Friday in Ukrainian drone attacks on Russia’s border regions, with several industrial sites also suffering damage.

Ukraine has pounded Russia’s energy infrastructure for months in an effort to cripple Moscow’s military might, leading to fuel shortages across Russia.

Putin has said the attacks are meant to sow discord among the public.

Valentin Demidov, mayor of Russia’s western city of Belgorod, said a woman had died in a car after being injured by shrapnel.

He said water and power supplies in the city, which is about 40km (25 miles) north of the border with Ukraine, had been disrupted.

Earlier on Friday, the Vesti news channel, citing local officials, said an industrial facility had caught fire after Ukraine attacked Belgorod and its surroundings with missiles.

Egor Kovalchuk, acting governor of Bryansk, another Russian border region, said a man had died in a village following a drone attack.

A fire also broke out at an industrial site in the western Smolensk region following a drone attack there, though no injuries were reported, local governor Vasily Anokhin wrote on Telegram.