Russian authorities said four people died in Ukrainian drone and missile attacks on Sunday, a day after Russia's bombing of Ukraine's second largest city of Kharkiv killed three people and left dozens in hospitals.

Three people — including two children — were killed by falling debris when five Ukrainian missiles were shot down in Sevastopol, a port city in Russia-annexed Crimea, said Mikhail Razvozhayev, the city's Moscow-installed governor. Close to a hundred people were injured, he said.

One person was killed and three injured in Russia’s Belgorod region, bordering Ukraine, when three Ukrainian drones attacked the city of Grayvoron, regional Gov. Vyacheslav Gladkov said.

Air defenses overnight shot down 33 Ukrainian drones over Russia’s western Bryansk, Smolensk, Lipetsk and Tula regions, the Russian Ministry of Defense said Sunday. No casualties or damage were reported.

The attacks came after Russia struck Kharkiv on Saturday afternoon with four aerial bombs, hitting a five-story residential building and killing three people. Regional Gov. Oleh Syniehubov said that 41 people were still being treated for injuries on Sunday.

In a video address following the attack, Ukrainian President Volodymyr Zelenskyy urged Ukraine’s partners to bolster its air defenses.

“Modern air defense systems for Ukraine — such as Patriots, accelerated training of our pilots for F-16s, and most importantly, sufficient range for our weapons — are truly necessary,” he said.

Two people were wounded by falling debris when two Russian missiles were shot down over the Kyiv region overnight, Ukraine’s air force commander Mykola Oleschuk said.

Regional Gov. Vadym Filashkin of Ukraine’s partly occupied Donetsk region said that Russian attacks on Saturday killed two people and wounded four.