KYIV, Ukraine — Powerful explosions shook Ukraine’s Zaporizhzhia region, the site of Europe’s largest nuclear power plant, the global nuclear watchdog said Sunday, calling for “urgent measures to help prevent a nuclear accident” in the Russian-occupied facility.

Rafael Mariano Grossi, the director general of the International Atomic Energy Agency, said two explosions — one Saturday evening and another Sunday morning — near the Zaporizhzhia plant abruptly ended a period of relative calm around the nuclear facility that has been the site of fighting between Russian and Ukrainian forces since Russia invaded on Feb. 24.

Fears of a nuclear catastrophe have been at the forefront since Russian troops occupied the plant during the early days of the war. Continued fighting in the area has raised the specter of a disaster.

In what appeared to be renewed shelling both close to and at the site, IAEA experts at the Zaporizhzhia facility reported hearing more than a dozen blasts within a short period Sunday morning, the statement said, adding that the IAEA team could see some explosions from their windows.

Several buildings, systems and equipment at the power plant — none of them critical for the plant’s nuclear safety and security — were damaged in the shelling, the IAEA said, citing information from the plant’s management. There were no reports of casualties.

Still, Grossi said reports of shelling were “extremely disturbing.” He added: “Whoever is behind this, it must stop immediately.

“As I have said many times before, you’re playing with fire!” Grossi said, and appealed to both sides in the conflict to urgently agree and implement a nuclear safety and security zone around the nuclear facility.

Russia has been pounding Ukraine’s power grid and other key infrastructure from the air, causing widespread blackouts for millions of Ukrainians amid frigid weather, with snow blanketing the capital, Kyiv, and other cities.

Elsewhere in the Zaporizhzhia region, Russian forces shelled civilian infrastructure in about a dozen communities, destroying 30 homes, the Ukrainian presidency said Sunday.

In the central Dnipropetrovsk region, one person was wounded and 20 buildings damaged in shelling of Nikopol, a city across the river from the Zaporizhzhia plant, the report said. Three districts in the northern Kharkiv region — Kupyansk, Chuguiv and Izyum — also came under Russian artillery fire in the past 24 hours.

In the eastern Luhansk and Donetsk regions, Russian shelling killed one person in Donetsk and damaged power lines, according to Ukrainian President Volodymyr Zelenskyy’s office.

The situation in the southern Kherson region “remains difficult,” the report said, citing the general staff of Ukraine’s armed forces. Russian forces fired tank shells, rockets and other artillery on the city of Kherson, which was recently liberated from Ukrainian forces, and the settlements of Chervyn Mayak, Kachkarivka, Tokarivka, Chornobayivka and Antonivka.

Shelling late Saturday struck an oil depot in Kherson, igniting a huge fire that sent black billowing smoke into the air.

Russian troops also shelled people lining up to get bread in the town of Bilozerka, wounding five, the report said.