While Mykolaiv has repeatedly been the target of Russian fire in recent days, Russian missiles also struck the town of Zaporizhzhia on Wednesday, an attack that could signal Moscow's determination to hold onto territory in Ukraine's south as it aims to fully conquer the east. Ukrainian forces have stepped up actions in a bid to reclaim more territory in the south.

Amid the artillery and missile strikes, the U.S. top diplomat accused Russia of committing a ``war crime`` by forcibly deporting hundreds of thousands of Ukrainian men, women and children to Russia in a bid to change Ukraine's demographic makeup.

Some of the civilian deaths occurred in Donetsk province, which is part of a region where pro-Russia separatists have fought the government for eight years and which the Kremlin is intent on capturing. The city of Bakhmut faced particularly heavy shelling as the current focus of Russia's offensive, Donetsk administrative chief Pavlo Kyrylenko said.

In adjacent Luhansk province, which Russian and separatist forces have all but conquered, Ukrainian soldiers battled to retain control of two outlying villages amid Russian shelling, Gov. Serhiy Haidai said.

Luhansk and Donetsk together make up Ukraine's Donbas region, a mostly Russian-speaking region of steel factories, mines and other industries vital to Ukraine's economy.

The Russians are ``deliberately turning Donbas into ashes, and there will be just no people left on the territories captured,'' Haidai said.

Russian artillery also rained down in northeast Ukraine, where a regional governor, Oleg Syniehubov, accused Russian forces of trying to ``terrorize civilians'' in Kharkiv, the country's second-largest city.

U.S. Secretary of State Antony Blinken, meanwhile, strongly condemned the ``unlawful transfer and deportation of protected persons`` from areas in Ukraine that Russia now controls.

``Russian authorities must?release those detained and?allow Ukrainian citizens forcibly removed or coerced into leaving their country the ability to promptly and safely return home,`` Blinken said in a statement.

Blinken said an estimated 900,000 to 1.6 million Ukrainian citizens, including 260,000 children, have been interrogated, detained and deported to Russia, in areas including the country's far east.

``Moscow's actions appear pre-meditated and draw immediate historical comparisons to Russian ``filtration'' operations in Chechnya and other areas,`` the U.S. official said. ``President Putin's `filtration' operations are separating families,?confiscating Ukrainian passports, and issuing Russian passports in an apparent effort to change the demographic makeup of parts of Ukraine.``

Bliken cited mounting evidence that Russian authorities are detaining, torturing or ``disappearing'' thousands of Ukrainian civilians who Russia considers threatening because of their potential ties to the Ukrainian army, media, government or civil society groups. Some Ukrainians, according to reports, have been summarily executed.

``President Putin and his government will not be able to engage in these systematic abuses with impunity. Accountability is imperative,`` said Blinken. ``The United States and our partners will not be silent. Ukraine and its citizens deserve justice.``

With Russia's sights set on the east, the Ukrainian military has tried to reclaim a captured city in the south. The Ukrainian military claimed Tuesday to have used missiles to destroy a Russian ammunition depot in occupied Nova Kakhovka, a city east of the Black Sea port of Kherson.

The precision of the depot strike suggested Ukrainian forces had employed U.S.-supplied multiple-launch High Mobility Artillery Rocket Systems, or HIMARS.

Russia's Tass news agency said the reported blast occurred when a mineral fertilizer storage facility exploded. Some ingredients in fertilizer can be used for ammunition.

Meanwhile, Ukrainian and Russian officials met face-to-face Wednesday for the first time in months. Military delegations from the two countries and Turkey were holding talks in Istanbul on a potential deal to get grain out of Ukraine's blockaded and mined ports through the Black Sea.

United Nations representatives also were involved in the talks. Ukraine is one of the world's largest exporters of wheat, corn and sunflower oil, but Russia's invasion has halted shipments, endangering food supplies in many developing countries and contributing to higher global prices.

The Ukrainian foreign minister says grain exports from his country's ports won't resume without security guarantees for ship owners, cargo owners and Ukraine as an independent nation.