KYIV, Ukraine -- Russia is using Europe's largest nuclear power plant as a base to store weapons including "missile systems" and shell the surrounding areas in Ukraine, an official with Kyiv's nuclear agency said Friday, while nearly the entire country was placed on air raid alert.
The president of Ukrainian nuclear agency Energoatom said the situation at the Zaporizhzhia nuclear plant was "extremely tense", with up to 500 Russian soldiers controlling the plant.
"The occupiers bring their machinery there, including missile systems, from which they already shell the other side of the river Dnipro and the territory of Nikopol," Pedro Kotin said in a televised interview, referring to the city across the water.
The plant in southwestern Ukraine has been under Russian control since the early weeks of Moscow's invasion, though it is still being operated by Ukrainian staff.
The most recent attack in the Dnipro region left three dead and 15 wounded after Russian "missiles hit an industrial enterprise and lively street nearby", regional governor Valentin Reznichenko said on Telegram.
The threat of air raids across most of Ukraine was also raised after strikes were reported in areas far from the front lines, with President Volodymyr Zelensky saying the Russian objective was to "cause maximum damage to Ukrainian cities".
"I'm urging you, once again: please don't ignore the air raid signals now," he said in his daily televised address.
Zelensky spoke after devastating Russian strikes in the central Ukrainian city of Vinnytsia killed nearly two dozen people, including three children, with rescue workers clearing debris throughout the day to locate survivors.
Four people were still missing and over 200 wounded, Zelensky said.
"Both at the national level and the international level, we will do everything to hold absolutely all Russian murderers responsible for what they have done," he said.
-Outpouring for slain toddler -
Russia claimed the strikes in Vinnytsia -- hundreds of kilometres away from frontline fighting -- had killed Ukrainian military officials and foreign arms suppliers.
But among those killed was four-year-old Liza Dmitrieva, who had Down's syndrome and whose death spurred an outpouring after footage of her final moments alive went viral on social media.
Officials initially believed Liza's mother had also been killed, but announced Friday she was alive and in "critical" condition after surgery.
First Lady Olena Zelenska said early Friday she was "horrified" by Liza's death and images of her overturned stroller released by local authorities.
The missile strikes on Vinnytsia are the latest attacks to carry a heavy civilian toll and come less than a week after strikes on Chasiv Yar in the Donetsk region left nearly 50 dead.
A strike on Friday hit the central square in Kramatorsk, a major city and an administrative centre of the Donbas. Authorities said no one was hurt since it happened during curfew.
"I have no words to describe the horror I experienced today," said Anastasiya, after rockets fell near her residential building.
"It's good that it fell outside and did not fly into the house. That was lucky."
Moscow launched its invasion on February 24 and the conflict has killed thousands of people, destroyed cities and forced millions to flee their homes.
The heaviest fighting recently in Ukraine has focused on the industrial Donbas region in the east, where grinding trench battles and artillery duels are morphing into a war of attrition.
-'Clearing' Donbas town -
The United Kingdom said Friday that the Kremlin "must bear the full responsibility" for the death of a British captive in east Ukraine.
"I am shocked to hear reports of the death of British aid worker Paul Urey while in the custody of a Russian proxy in Ukraine," Foreign Secretary Liz Truss said.
Moscow-backed separatists said Friday they were closing in on their next target, Siversk, after wresting control of sister cities Lysychansk and Severodonetsk -- about 30 kilometres (18 miles) to its east -- two weeks ago.
And Donetsk separatist official Daniil Versonov said rebel fighters were "clearing" eastern districts of Siversk in small groups.
Ukraine has repeatedly urged allies to supply it with advanced, long-range precision artillery systems that would allow it to target Russian forces deeper inside Ukrainian-held territory.
Defence Minister Oleksiy Reznikov said Friday that Ukraine had taken delivery of its first batch of sophisticated M270 rocket systems, adding to a growing arsenal of Western-supplied artillery Kyiv says is changing dynamics on the battlefield.
In his address, Zelensky said the United States would include additional aid for his country in a new budget bill, including the development of Ukraine's air capabilities to "significantly strengthen our defence potential".