Russia says at least 14 people, including two children, were killed in Ukrainian shelling on the Russian city of Belgorod on Saturday, vowing to respond.

The deaths on Saturday were the result of a “massive” attack on downtown Belgorod, according to Russian state news agency TASS, quoting the Russian emergencies ministry.

“This crime will not go unpunished,” the Russian Defense Ministry said in a statement.

“The Kyiv regime … is trying to divert attention from the defeats on the front lines and to provoke us into taking similar actions.”

Following the attack, Russia requested an emergency meeting of the United Nations Security Council, Russia’s First Deputy Permanent Representative to the UN, Dmitry Polyanskiy, said Saturday.

Saturday’s shelling comes after Russia launched overnight Thursday into Friday its biggest air attack on Ukraine since the start of its full-scale invasion, resulting in at least 40 deaths and more than 150 injuries.

Ukrainian attacks on Russian regions near the border have continued almost daily for over a year, sometimes resulting in civilian casualties, but if confirmed this is one of the single deadliest incidents.

Russian President Vladimir Putin has been briefed about the attack in Belgorod, the Kremlin said, ordering a health ministry team and emergencies ministry rescuers to be sent to the city to help those affected.

About 40 civilian facilities have been damaged in the city due to the shelling, which caused 10 fires which have since been extinguished.

Russian authorities said Belgorod was also shelled Friday night with one civilian killed, the region’s governor Vyacheslav Gladkov said. Four others, including a child, were injured, he added.

On Saturday, a child also died as a result of Ukrainian shelling in Russia’s Bryansk region, the region’s Governor Aleksandr Bogomaz said.

Russia’s defense ministry said it destroyed 32 Ukrainian UAVs flying over the Russian regions of Bryansk, Oryol, Mursk, and Moscow, according to a Telegram post by the defense ministry Saturday.

Ukraine has not publicly commented on the incidents and rarely claims responsibility for attacks on its neighbor.

Rescuers comb through Kyiv rubble

The toll from the Russian strikes on Ukraine – which saw an unprecedented number of drones and missiles fired at targets across the country – meanwhile continued to mount.

A 77-year-old man died from his injuries in the city of Odesa, Oleh Kiper, the head of the Odesa region military administration said, bringing the total killed to 40.

The man was critically injured when a missile hit a three-storey building in the center of Odesa, Kiper added.

Schools, a maternity hospital, shopping arcades and blocks of flats were among the buildings hit in Friday’s barrage, prompting widespread international condemnation and renewing calls for more military aid.

The toll in the capital Kyiv rose to at least 16 after the bodies of more civilians were recovered from the rubble of a warehouse, Mayor Vitaliy Klitschko said Saturday. All the deaths in Kyiv occurred at the warehouse.

“The attack on the capital city on December 29 was the largest in terms of civilian casualties” since the start of the full-scale invasion, he said.

“Rescuers are working and will continue to clear the rubble until tomorrow,” Klitschko said. “January 1 will be declared a Day of Mourning in Kyiv.”

During the wave of strikes, Poland’s military authorities claimed that an “unidentified airbourne object” briefly entered its airspace.

Russia said it would not give any explanation “until concrete evidence is presented.”

NATO Secretary General Jens Stoltenberg wrote on X that NATO remained vigilant over the incident.