Flooding in the southern Russia region of Orenburg has worsened overnight as water levels continued to rise, forcing officials to step up evacuation efforts.
"The flood situation is developing according to the worst case scenario," Russian state-owned news agency TASS reported on April 7, citing regional authorities.
The Russian government has declared the flood-hit areas a federal emegency.
Sergei Salmin, the mayor of Orenburg, the regional capital with a population of 500,000, urged residents in danger zones to leave immediately.
"Those who refuse to leave the danger zone voluntarily, we will evacuate forcibly with the participation of police officers," he said in a statement on Telegram.
He called the situation critical and warned that the water level would rise in the coming days.
The situation in the Orenburg region, which borders northern Kazakhstan, took a dangerous turn on April 5, when water in the Ural River breached a 10-year-old dam near Orsk, flooding the town of about 200,000.
More than 6,300 homes in the region have been flooded, including about 4,500 in Orsk, the most impacted town.
Russian rescuers evacuate residents during a flood in the town of Orsk on April 7.
The water level in Orsk rose about 28 centimeters overnight forcing the local refinery to shut on April 7, officials said. The Orsk refinery has a capacity of about 130,000 barrels a day.
More than 4,400 people have been evacuated to date, though that number is expected to rise in the coming days. The flooding has knocked out power to more than 8,000 homes.
Russia’s Emergencies Ministry said it has enough forces and means in the region to cope with the disaster.
In some areas of Orsk, the water has reached first-floor windows and some people are moving around by boat.
Regional authorities said they found four people dead in the flooded zone but claim that none of them drowned. The authorities said two died of heart attacks and one committed suicide. The cause of the fourth death was not specified, but was designated as "natural," state-owned RIA Novosti reported.
Russian prosecutors have opened a criminal investigation into the construction of the Orsk dam.