A rescue worker with a dog searches for victims in a damaged apartment building after it was hit by a Russian air bomb in Kharkiv, Ukraine on Saturday. At least three people were killed in a Russian bomb attack on Ukraine’s second city, Kharkiv, on Saturday afternoon, Ukrainian President Volodymyr Zelensky said. Andrii Marienko/Associated Press

KYIV, Ukraine — Russian authorities said four people died and over 100 were wounded in Ukrainian drone and missile attacks on Sunday, while the second day of Russia’s aerial bombing of Kharkiv in northeastern Ukraine killed at least one person.

Five 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. Russian state news agency RIA Novosti, citing the Health Ministry, said 124 people were wounded.

Razvozhayev declared Monday a day of mourning in the city, with public events canceled.

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.

A fresh attack on Kharkiv killed at least one person and wounded 11 on Sunday, according to local officials. Mayor Ihor Terekhov said the city was attacked by a guided bomb and that around half of Kharkiv was without electricity because of the strike.

Sunday’s 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 Zelensky 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.

In other developments, the Ukrainian Navy released photos Sunday that it says confirm the destruction of a warehouse in Russia’s southern Krasnodar region used to launch and store Iranian-designed Shahed drones.

Navy officials said training instructors and cadets were killed in the attack on Friday night. Moscow has not yet commented on the reports, but officials said air defenses shot down several drones in the region overnight on Friday.