Russia-Ukraine updates: Russian missiles hit close to nuclear reactors: IAEA director

In a televised address to his nation, Ukrainian President Volodymyr Zelenskyy described the Russian shelling Sunday of Mykolaiv in southern Ukraine as "one of the most brutal" in the five-month war.

Zelenskyy said the missile attacks hit residential buildings, schools, industrial facilities and other social infrastructure.

He also expressed condolences over the deaths of billionaire Ukrainian farmer Oleksiy Vadaturskyy and his wife, Raisa, who died when a missile struck their home in Mykolaiv.

Zelenskyy called Vadaturskyy, founder of one of the largest Ukrainian agricultural companies, "the hero of Ukraine."

"It is exactly such people, such companies, our Ukrainian south that have guaranteed the world's food security. It has always been so. And it will be so again," Zelenskyy said. "The Russian terrorists should not even hope that they will be able to destroy the social and industrial potential of Ukraine and walk through the ruins."

Zelenskyy said the Russian army is attempting to strengthen its positions in the occupied areas of the south by moving part of its forces to the Kherson and Zaporizhzhia regions there from the east.

"But this will not help them there," Zelenskyy said. "None of the Russian strikes goes unanswered by our military and intelligence officers. The Armed Forces of Ukraine are ready to respond to any new activity of the occupiers."

Zelenskyy added, "Strategically, Russia has no chance of winning this war. And it is necessary to hold on, so that even at the tactical levels, the terrorist state feels its defeat. We have to hold on in the south, in the east and everywhere."

Photos show the destruction caused when a small Ukrainian drone loaded with explosives struck the headquarters of the Russian Black Sea fleet in Crimea.

Russian military officials said at least five people were wounded in the attack Sunday in Sevastopol.

Russian media posted photos showing light debris scattered around an entrance to the building in Sevastopol.

Other photos showed Sevastopol Gov. Mikhail Razvozhayev standing outside the Russian Black Sea Fleet headquarters inspecting the damage.

The Black Sea Fleet's press service reported that the drone explosive appeared to be homemade and described it as a “low-power” device, according to The Associated Press. It was not immediately clear where the drone was launched from.

The attack appears highly symbolic, coming as Russia marks Navy Day and showing Ukraine’s reach to strike targets in Crimea.

Putin is attending a huge naval parade in St Petersburg Sunday. Following the strike, all celebrations in Sevastopol were reportedly canceled.

-ABC News' Patrick Reevell

A billionaire Ukrainian farmer who plays a crucial role in the country's agricultural industry was killed when a Russian missile struck his mansion just as Ukrainian grain shipments are about to resume.

Oleksiy Vadaturskyy, one of Ukraine’s richest men, died when a Russian missile struck a wing of his large home in the southern city of Mykolaiv, officials said.

Mykhailo Podolyak, a top aide to Ukrainian President Volodymyr Zelenskyy, accused Russia of deliberately targeting Vadaturskyy.

Video from the scene of the missile strike shows one wing of the large mansion collapsed.

"Vadaturskyy was one of the largest farmers in the country, a key person in the region and a large employer," Podolyak said. "The accurate hitting of the missile not just in the house, but in a specific wing -- the bedroom -- leaves no doubts about the guidance and correction of the impact. Once again: Vadaturskyy was made a specific target."

Podolyak alleged the killing of Vadatursky is part of a deliberate wave of atrocities aimed at breaking Ukrainian morale, including the alleged massacre of POWs.

"Every crime makes us feel pain, but we live it and only become more hardened,” Podolyak said.

The death of Vadaturskyy, who Podolyak said had direct relations to the grain industry, came after Zelenskyy visited Odesa on Friday to watch crews load ships with grain that has been trapped by Russia’s five-month-old war.

Ukraine is a top global exporter of wheat, sunflower oil, corn and barley and its inability to export its agricultural products has led to a spike in food prices worldwide and exacerbated a global food crisis.

-ABC News Patrick Reevell

Ukrainian President Volodymyr Zelenskyy announced a mandatory evacuation of the Donetsk region in eastern Ukraine as fighting intensifies.

"The sooner it is done, the more people leave Donetsk region now, the fewer people the Russian army will have time to kill," Zelenskyy said in a national address on Saturday.

The president additionally urged those in the broader Donbas region "in the areas of the fiercest fighting" to leave.

Governmental officials said they have activated a civil defense law that allows for a mandatory evacuation to be declared. People can still refuse to leave, provided they sign a disclaimer saying they understand all the risks, officials said.

Officials are urging people to leave ahead of winter, as the region's natural gas supplies have been destroyed and there will be no heat.

There are around 200,000 people still in Donbas who need to leave, according to Ukrainian's deputy prime minister, Iryna Vereshchuk.

-ABC News' Patrick Reevell