Baton Rouge, August 16

As many as 30,000 people have been rescued following unprecedented floods in the southern US state of Louisiana, including a 78-year-old woman who spent a night stranded on a tree, police said last night.

Residents awoke today to find their homes and businesses still surrounded by muddy water, without clear answers about when the epic flooding that has killed at least seven is expected to recede.

Thousands were hunkering down in shelters after waterways in the southern part of the US state overflowed their banks following more than 50 cm of rain between Thursday and Saturday.

“Our state is experiencing a historic flooding event that is breaking every record,” Louisiana Governor John Bel Edwards said in a statement last night.

“This event is ongoing, it is not over,” he said. “We do not know when the floodwaters will recede, and they will continue to rise in some areas.”

Police said the Louisiana National Guard would assist evacuees in the massive shelters, which included a film studio complex in the state capital Baton Rouge and an entertainment centre in the city’s downtown area. Floodwaters even reached the rooflines of some homes in the worst-hit areas.

Seven people were confirmed dead, Louisiana State Police Superintendent Colonel Mike Edmonson said, noting the toll could rise in coming days.

“Once the water recedes, all these homes that are completely covered with water, we got to go to every single one of those and go inside of them and check for anybody who might be in those areas,” he told CNN.

Some 40,000 homes and business were reported to be without power.

The White House declared four parishes — equivalent to counties in other states — major disaster areas. “I fully expect that more parishes will be added to the declaration on a rolling basis,” Edwards said.

Floodwaters appeared to be receding in some areas, but were flowing into others. The National Weather Service continued to issue flood warnings in effect through early today, saying water in many areas would not recede at least for another day.

The Amite River, the source of flooding for many areas, had risen 4.3 metres above flood level in one reading, besting a previous record set during flooding in April 1983, the NWS said. The agency forecast the river would not fall below flood level until Wednesday morning.

In some areas, clean-up work was already beginning, with members of the Life Tabernacle Church in Baton Rouge dumping water-damaged pews on a growing pile of debris outside. Inside, a young boy rode his bicycle around the now-empty church.

The White House declaration makes emergency federal funding available to support rescue crews and recovery efforts.

The Federal Emergency Management Agency today began asking those affected by the floods to apply for assistance, and officials said 11,000 people had already registered early in the day.

The American Red Cross called the flooding the worst since Superstorm Sandy hit coastal areas in New York and New Jersey in 2012.

Many parishes in Louisiana were collecting donations for flood victims, including food, water, blankets, school uniforms, bedding and hygiene products.

Louisiana was devastated by Hurricane Katrina in 2005 and authorities learned from that disaster that many people are reluctant to leave their homes without their pets, even when conditions are life-threatening.

Several shelters in the Baton Rouge area were accepting evacuees with four legs.

The NWS said other areas of the United States faced threats of flash floods this week.