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

United Nations Secretary-General Antonio Guterres is "calling for all military activities" around the Zaporizhzhia Nuclear Plant in southern Ukraine "to cease immediately," and for armies not "to target its facilities or surroundings."

Ukraine's nuclear regulator Energoatom said Russian forces shelled the plant for a third time on Thursday, hitting close to the first power unit. Earlier on Thursday, Energoatom said five rockets struck the area around the commandant's office, close to where the radioactive material is stored.

Yevgeny Balitsky, the Russian-installed interim governor of Zaporizhzhya Oblast, issued a statement claiming Ukrainian forces struck the plant, hitting close to an area with radioactive material.

Guterres said he's appealed to all parties to "exercise common sense" and take any actions that could endanger the physical integrity, safety or security of the largest nuclear power plant in Europe.

"Instead of de-escalation, over the past several days there have been reports of further deeply worrying incidents that could, if they continue, lead to disaster," he said, adding that he’s "gravely concerned."

Rafael Grossi, director general of the International Atomic Energy Agency, pleaded with the U.N. Security Council Thursday to allow for an IAEA mission to visit the plant as soon as possible. He said the situation at the plant is deteriorating rapidly and is "becoming very alarming."

-ABC News' Christine Theodorou, Fidel Pavlenko, Natalya Kushnir and Natalia Shumskaia

Russian shelling killed at least 13 civilians in eastern Ukraine's Dnipropetrovsk region early Wednesday morning, local authorities said.

At least 11 others were injured, with five people remaining in critical condition, according to Dnipropetrovsk Oblast Gov. Valentyn Reznichenko, who said Russian forces fired 80 rockets at residential areas in the region.

"They deliberately and sneakily struck when people were sleeping in their homes," Reznichenko said in a statement Wednesday.

Russian shells hit civilian objects in the region's southern Nikopol district from the area of the Zaporizhzhia nuclear power plant, which is occupied by Russian troops some 30 miles away, according to Ukrainian President Volodymyr Zelensky's chief of staff, Andriy Yermak.

More than 20 high-rise buildings, two schools, a city council building and several other administrative buildings in the city of Marhanets were damaged in the attack, Yermak said.

The city of Nikopol and the surrounding areas have been subject to regular shelling for several weeks. Russian forces fired 120 MLRS missiles at Nikopol early Tuesday, damaging several residential and commercial buildings.

Russian missiles also struck the southern city of Mykolaiv on Wednesday, injuring three people, including a child.

Meanwhile, explosions and casualties were also reported in the eastern Sumy region on Wednesday morning.

-ABC News' Edward Szekeres, Yuriy Zaliznyak and Max Uzol

Russian forces shelled the outskirts of Zaporizhzhia overnight, killing at least one civilian, the city's acting mayor, Anatoly Kurtev, said Wednesday.

The strike on the Kushugum community left three homes destroyed and almost 30 others damaged. The civilian who died was a woman, according to Kurtev.

That same night, Ukrainian troops defending the Zaporizhzhia region shot down two Russian missiles, Kurtev said, citing "preliminary information."

"Take care of yourself and your loved ones," the acting mayor said in a statement on Telegram. "Don't ignore the air alarm!"

A source familiar with the operation confirmed to ABC News that Ukraine was behind a Tuesday explosion in Russia-annexed Crimea. One person died from the blasts in Novofedorivka in Crimea, Russia's semi-official Interfax reported, citing Crimean official Sergei Aksyonov.

This is the first major attack in Crimea since the war began in February.

-ABC News’ Britt Clennett and Dada Jovanovic