Ukraine said Russian forces have blown up a giant dam in the country’s south, unleashing a torrent of floodwater that threatens residents and complicates the battlefield separating their two armies along the Dnipro river.

The blast at the Kakhovska hydroelectric power plant is causing a rise in water levels that puts 10 villages on the western bank of the Dnipro and a part of the city of Kherson at risk of flooding, the Ukrainian Interior Ministry said on Telegram, urging people to prepare for evacuation.

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More than 80 settlements and Kherson city lie within the flood zone “which could lead to hundreds of thousands of victims,” Ukrainian Deputy Infrastructure Minister Mustafa Nayyem said on Twitter. The hydro power station built in 1956 provides electricity to more than 3 million people and is a “crucial part of the country’s energy infrastructure,” he said.

As of 7:30 a.m. in Ukraine, eight villages and a district of Kherson were flooded or partially flooded and some 16,000 people in the region are in a “critical zone,” Governor Oleksandr Prokudin said in a video on his Telegram channel. The first train evacuating people from the area will leave at noon, he said.

The Zaporizhzhia nuclear power plant in the south of Ukraine, which has been occupied by Russian forces for more than a year, uses water from the Kakhovska reservoir for cooling its reactors. The situation at the plant is under control now and the cooling reservoir is full, Ukraine’s nuclear power operator Energoatom said on Telegram.

President Volodymyr Zelenskiy summoned an urgent meeting of Ukraine’s national security and defense council. He blamed the attack on Russia, saying on Telegram that the destruction of the dam “only confirms for the whole world that they must be expelled from every corner of Ukrainian land.”

Wheat futures soared as much as 3% in Chicago as traders assessed the implications. The dam’s destruction “looks like a big escalation with dire consequences and huge headline risk,” Andrey Sizov, managing director at agricultural consultant SovEcon, said in a tweet.

Russia hasn’t commented on the incident officially so far. After being forced to withdraw from the city of Kherson in November, its forces are dug in on the opposite side of the Dnipro river as Moscow braces for a Ukrainian counteroffensive aiming to reclaim territory that was occupied early in President Vladimir Putin’s February 2022 invasion.

Ukraine has warned repeatedly in the past year that Russia may attempt to blow up the dam to try to stall its advance. Russia blew up the dam to try “to create insurmountable obstacles” for the Ukrainian military, Mykhailo Podolyak, an advisor to Ukrainian presidential office said on Twitter. “Colossal damage will be done to the environment.”

The scale of the damage, changes in water levels and areas in danger of flooding were being evaluated early Tuesday, the southern military command of the Ukrainian Armed Forces said on Facebook.

--With assistance from Daryna Krasnolutska.