Hundreds of people have been evacuated from settlements along the southern stretch of Ukraine’s Dnipro River after water burst through the breached Nova Kakhovka dam, submerging streets and town squares.

The collapse of the structure at the southern tip of the vast Kakhovka Reservoir unleashed a torrent of water on Tuesday, adding to misery for thousands of people who have been caught on the front lines of the war between Ukraine and Russia.

Looking downstream, Russia controls the left bank of the Dnipro and the dam itself, and Ukraine holds the right bank. Each side has blamed the other for causing the damage.

Footage posted on social media shows severe flooding in the Russian-controlled town of Nova Kakhovka, which is next to the dam.

Its Russian-installed mayor said water levels had risen to more than 11 metres (36 feet) and some residents had been taken to hospital. He did not give details.

In one clip, swans swim past the ornate city council building, and in another, a sports stadium next to the river is inundated.

The Russian-installed administration of Ukraine’s Kherson region said it was preparing to evacuate three districts – Nova Kakhovka, Golo Pristan and Oleshky. The latter two lie across the mouth of the Dnipro River from the Ukrainian-held regional capital, also named Kherson.

Water levels there had already risen by more than a metre (3.3 feet), residents said, and were expected to rise further.

“The water flow in the Dnipro River and its tributaries is very powerful,” Kherson resident Oleksandr Syomyk said as he stood beside the swollen river.

Ukrainian police released a video showing an officer carrying an elderly woman to safety and residents wading to safety through knee-deep water in the Kherson region.

Oleksandr Tolokonnikov, a senior official in Ukraine’s Kherson military administration, warned that worse was to come.

“Tomorrow there will be a peak [in the flooding]. Then there will be a decline,” he said in an online media briefing.

“We already evacuated about 1,000 people. We have about 50 buses shuttling between Kherson and the affected villages. In Kherson, we have four evacuation sites prepared.”

The dam supplies water to farms in southern Ukraine and the Russian-occupied Crimean Peninsula. It also cools the Russian-held Zaporizhzhia nuclear plant.

The heavy damage the dam has sustained creates a new humanitarian disaster just as Ukraine is unleashing a long-awaited counteroffensive to drive Russian troops from its territory.