Some 42,000 people are at risk of flooding in Russian-Ukrainian controlled areas along the Dnieper river after a dam collapsed, as the UN aid chief warned of “serious and far-reaching consequences”.

Ukraine and Russia blame each other for the collapse of the massive dam on Tuesday, which flooded a swath of Ukraine’s war zone and forced thousands of people to flee. Ukraine said Russia committed a deliberate war crime by blowing up the Soviet-era Nova Kakhovka dam, which fed a hydroelectric power station. The Kremlin blamed Ukraine, saying it was trying to divert attention from launching an expected counteroffensive that Russia says is in trouble.

UN humanitarian chief Martin Griffiths told the Security Council that the dam breach “will have serious and far-reaching consequences for thousands of people in southern Ukraine, on both sides of the front line. , for the loss of homes, food, drinking water and livelihoods”. “The magnitude of the catastrophe will not be fully perceived until the next few days,” he said. No deaths were initially reported, but US spokesman John Kirby said the flooding had probably caused “a lot of deaths”.

Ukrainian authorities estimate that some 42,000 people are at risk from flooding, which is expected to peak on Wednesday. In the city of Kherson, some 60 kilometers downriver from the dam, the water level rose 3.5 meters on Tuesday, forcing residents to wade through knee-deep water to evacuate the city, carrying bags of plastic bags full of belongings and small pets in carriers.

“Everything is submerged in the water, all the furniture, the fridge, the food, the flowers, everything is floating. I don’t know what to do,” said Oksana, 53, when asked about her house.

Buses, trains and private vehicles mobilized to save the population of some 80 communities threatened by flooding. In Kherson, the thunder of artillery sent people running as they tried to flee. Overnight, Reuters reporters heard four artillery rounds near a residential neighborhood where civilians were being evacuated. Residents of flooded Nova Kakhovka, on the Russian-controlled bank of the Dnieper, told Reuters some had decided to stay despite being ordered to leave. “They say they are ready to fire without warning,” said one man, Hlib, referring to the encounters with the Russian soldiers.

The Kazkova Dibrova Zoo, located on the Russian-controlled shore, was completely flooded and its 300 animals had died, a representative said on the zoo’s Facebook account. “Every hour more and more water comes in. It’s very dirty,” Yevheniya, a woman from Nova Kakhovka, said by phone.

The United States said it was not sure who was responsible, but US Deputy Ambassador to the UN Robert Wood told reporters it would make no sense for Ukraine to destroy the dam and harm its own people. The Geneva Conventions prohibit attacking prizes in war due to the danger they pose to the civilian population.

Ukrainian President Volodymyr Zelensky stated in a videotaped speech that his prosecutors had turned to the International Criminal Court regarding the dam. Earlier, he said on Telegram that the Russian military had blown up the facility from inside.

“Residents are sitting on the roofs of their houses waiting to be rescued… This is a Russian crime against people, nature and life itself,” Oleksi Kuleba, a senior member of Zelensky’s team, said on Telegram. The dam supplies water to a large agricultural area in southern Ukraine, including the Russian-occupied Crimean peninsula, as well as cooling the Russian-owned Zaporizhia nuclear power plant.

Satellite images taken Tuesday afternoon by Maxar Technologies showed submerged houses and other buildings, many showing only their rooftops. Maxar said images of more than 2,500 square kilometers between Nova Kakhovka and the Dniprovska Gulf, southwest of the Black Sea city of Kherson, showed numerous towns and villages inundated.

The UN nuclear watchdog said the Zaporizhia power station, located upstream in the reservoir, should have enough water to cool its reactors for “a few months” from a separate pond. As kyiv prepares for its long-awaited counteroffensive, some military analysts said the flooding could benefit Russia by slowing or limiting any Ukrainian advance along that part of the front line. On the other hand, Zelensky claimed to have received “a serious and powerful offer” from countries willing to provide F-16 fighter jets, which is a boost to the Ukrainian army.

“Our partners know how many planes we need,” Zelensky said in a statement posted on his website. “I have already received information from some of our European partners about the number… It is a serious and powerful offer.” kyiv now awaits a final agreement with its allies, including “a joint agreement with the United States,” Zelensky said. It is not clear which of Ukraine’s allies are willing to provide it with the reactors.