ODESA, Ukraine — President Volodymyr Zelensky of Ukraine said he visited the flood-stricken Kherson region on Thursday, where rescue efforts pushed ahead after the destruction of a dam on the Dnipro River, as he called for “a clear and quick global response” to the disaster.
An explosion early Tuesday at the Kakhovka dam sent a torrent of water from a reservoir upstream coursing down the river, flooding much of the Ukrainian-controlled city of Kherson and dozens of settlements on both sides of the Dnipro, an active war zone that cuts through Russian- and Ukrainian-controlled territory.
“I visited a crossing point where people are being evacuated from flooded areas,” Mr. Zelensky said in a statement on the Telegram messaging app, in which he thanked rescue workers. “Our task is to protect lives and help people as much as possible.”
As of Thursday morning, the average flood level in the Kherson region stood at more than 18 feet, Ukrainian regional officials said, adding that about 230 square miles remained underwater in a region that spreads across 11,000 square miles.
Of the area underwater, 32 percent is on the Ukrainian-controlled west bank and 68 percent on the Russian-controlled east bank, said Oleksandr Prokudin, the head of Ukraine’s regional military administration in Kherson.
Russian-appointed officials in the occupied city of Nova Kakhovka, adjacent to the dam, said that five people had died in flooding, the Russian state-run RIA Novosti news agency reported. Dozens more in Russian territory were hospitalized, officials said, but the full scale of the toll may not be known for days until floodwaters recede.
The Dnipro marks a dividing line between Russian and Ukrainian forces in parts of the region, and officials and residents said that Russian shelling across the river has impeded humanitarian efforts.
On Wednesday, Mr. Zelensky called for “a clear and quick global response” to the flooding and criticized international agencies that were “not capable of taking action.”
“Every death over there marks an indictment of the existing international mosaic, of international organizations which have gotten out of the habit of saving lives,” Mr. Zelensky said on Telegram.
During peacetime, it is not uncommon for international aid agencies to mobilize quickly and organize a relief effort, as they did after the deadly earthquakes struck Syria and Turkey in February. But providing assistance is much more complicated in a war zone.
The International Committee of the Red Cross said on Twitter on Wednesday that its teams in Ukraine were “working around the clock” to assist and evacuate those affected by floods, and assessing what could be done to support the humanitarian response.
Residents said that intense shelling of Ukrainian-controlled territory in the flood zone had continued since the dam broke early Tuesday, with some describing fleeing the area under fire. Mr. Prokudin said that Ukraine recorded 353 shells from Russian mortars, artillery, rocket systems, drones, tanks and aircraft into the region on Tuesday.
On Thursday, the Ukrainian authorities said they had evacuated almost 2,000 people from the Kherson flood zone, including more than 100 children, and had set up nine evacuation points. But the State Emergency Service also warned of the dangers of mines and unexploded ammunition being dislodged by floodwaters.
On the Russian-occupied side of the river, about 4,500 people had been evacuated as of Thursday, the Russian state-run Tass news agency said on Telegram, citing Kremlin-appointed officials in the region. The total number brought to safety remains a fraction of the roughly 41,000 people on both sides of the Dnipro estimated by Ukraine to be at risk from the flooding.
President Emmanuel Macron of France spoke with Mr. Zelensky on Wednesday and said that his country would be sending humanitarian aid to Ukraine “very quickly,” including a first convoy of around 10 tons of supplies Kyiv has asked for, including water purification tools and portable cisterns.
Aurelien Breeden and David Kurkovskiy contributed reporting.