STORY: Footage released by Ukraine's emergency services on Tuesday shows rescue workers motor-boating through a flooded residential neighborhood in the Kherson region.
The area was inundated after a massive dam holding back a reservoir was destroyed, sending a deluge downstream into a war zone and forcing villagers to flee.
These rescuers appear to lift an elderly resident from their home in a rug.
Drone footage from a Russian news agency shows what's left of the Soviet-era Nova Kakhovka dam.
Russia has controlled the dam since early in its 15-month-old invasion.
Ukraine accused Russia of blowing it up, calling the act a deliberate war crime.
"The Kakhovka disaster is yet another proof that Russia is a terrorist state."
Ukrainian Foreign Minister Dmytro Kuleba on Tuesday released a message calling for an emergency meeting of the United Nations Security Council to discuss the situation.
But the Kremlin said it was Ukraine that sabotaged the dam.
Russia's defense minister on Tuesday said Kyiv destroyed it as part of an effort to redeploy military units.
Neither side has so far presented evidence for its claims.
"As you might expect, we've been closely monitoring the impacts of that destruction, which has triggered massive flooding in Ukraine and resulted in the evacuation of, at the very least, thousands of Ukrainians."
White House national security spokesperson John Kirby said Washington had not yet determined who or what caused the dam's destruction.
"We cannot say conclusively what happened at this point."
Nova Kakhovka's destruction comes amid signs Ukrainian forces may be ramping up a long-awaited counter-offensive against Russian troops occupying parts of the country's east.
"Blowing up the dam of Kakhovka creates a very good defending position for Russians, who expect offensive activity of Ukrainian army."
Maciej Matysiak is a former deputy head of Poland's military counter-intelligence service. He said Moscow might have an interest in flooding the region in an effort to stop Kyiv's forces from advancing anytime soon.
"At least a month, it excludes this area terrain of use of heavy equipment like tanks or APCs [armored personnel carriers], or heavy armored vehicles. But at the same time, it covers for Ukrainian safety on this flank because during expected offensive of Ukrainian army, Russians won't be able to operate in this direction."
Meanwhile the humanitarian toll is expected to be severe, displacing even more civilians in a conflict that, according to the United Nations High Commissioner for Human Rights, has already sent eight million refugees into Europe and internally displaced another five million inside Ukraine.