KYIV, Ukraine (AP) — Russian forces stepped up their battle to seize one of the dwindling number of cities in embattled eastern Ukraine not already under their control while continuing to fire on towns and villages in the country’s north and south, Ukrainian officials said Saturday.

Russian shelling collapsed balconies and blew out windows in the southern region of Mykolayiv, injuring at least nine civilians, authorities said. A five-story apartment building and private homes in the town of Voznesensk were badly damaged, the Black Sea region’s governor said.

“As of 13.30 p.m. (local time) - nine wounded, including four children. All children in a serious condition. Ages range from 3 to 17 years,” Gov. Vitaliy Kim wrote in a Telegram post. He added that a young girl lost an eye as a result of Saturday’s attack.

Reflecting the broadening frontlines of the nearly 6-month war in Ukraine, a Ukrainian airstrike hit targets in the largest Russian-occupied city in the southern Zaporizhzhia region, according to Ukrainian and Kremlin-backed local officials.

The Ukrainian mayor of Melitopol said preliminary reports pointed to “a precise hit” on a Russian military base. The head of the Kremlin-backed administration said the attack damaged residential areas and slightly injured one civilian.

In its daily update, the General Staff of the Armed Forces of Ukraine said intensified combat took place around Bakhmut, a small city whose capture would enable Russia to threaten the two largest remaining Ukrainian-held urban centers in the eastern Donbas region.

Bakhmut has for weeks been a key target of Moscow’s eastern offensive as the Russian military tries to complete a months-long campaign to conquer all of the Donbas, an industrial region that borders Russia where pro-Moscow separatists have self-proclaimed a pair of independent republics.

A local Ukrainian official reported sustained fighting Saturday morning near four settlements on the border between Luhansk and Donetsk provinces, which together make up the contested region.

Luhansk Gov. Serhii Haidai did not name the settlements or mention Bakhmut, which lies around 25 kilometers (16 miles) from the border between the two provinces. Russian forces overran nearly all of Luhansk last month and since then have focused on capturing Ukrainian-held areas of Donetsk.

Russian shelling killed seven civilians Friday in Donetsk province, including four in Bakhmut, Gov. Pavlo Kyrylenko wrote Saturday on Telegram. Taking Bakhmut would give the Russians room to advance on the province’s main Ukrainian-held cities, Kramatorsk and Sloviansk.

The General Staff update said Sloviansk and Kramatorsk also were targeted Friday along with the Kharkiv region to the north, home to Ukraine’s second-largest city.

Neither Moscow nor Kyiv commented on the airstrike aimed at Russian-occupied Melitopol in southern Ukraine. Earlier Saturday morning, The Russian Defense Ministry’s spokesman, Igor Konashenkov, claimed that pro-Russia forces had shot down Ukrainian shells near the city, as well as near a key power station in the Kherson region, which the Russians seized early in the war.

The head of the Kremlin-installed administration in Melitopol confirmed Saturday that the city had come under Ukrainian fire.

“During the night, the Kyiv regime launched two attacks on our beautiful Melitopol, on residential areas of the city. Russian air defense systems shot down missiles, but as a result of the shelling, the houses of residents on (two) streets were partially destroyed and damaged,” Galina Danilchenko said on Telegram.

The Ukrainian mayor of Melitopol, Ivan Ferodov, said local Ukrainian authorities were gathering information on the strike.

“Tonight, there were powerful explosions in Melitopol, which the whole city heard,” Ferodov said. “According to preliminary data, (it was) a precise hit on one of the Russian military bases, which the Russian fascists are trying to restore for the umpteenth time in the airfield area,”

Shortly after Dalnichenko’s post, Ferodov reported that residential areas in the city were hit but he blamed that strike that destroyed about 10 homes on the Moscow-backed forces stationed in Melitopol. He also reiterated his earlier claim that a Ukrainian airstrike badly damaged a Russian military base.

The Ukrainian governor of the southern Zaporizhzhia region, which is partly controlled by Russia and where Melitopol is located, said late Friday evening that a child was seriously injured by Russian shelling on the outskirts of the regional capital that day.

The governor, Oleksandr Starukh, said on Telegram that the 8-year-old girl remained on a ventilator following surgery, but was in “stable” condition. Starch added that the same attack in the city of Zaporizhzhia left two adult civilians with “injuries of moderate severity.”

Ukrainian officials have indicated plans for a counter-offensive to win back occupied areas in the country’s south while Russia had most of its focus on the east.

Local authorities reported renewed Russian shelling overnight along a broad front, including of the northern Kharkiv and Sumy regions, which border Russia, as well as of the eastern Dnipropetrovsk region and Mykolayiv.