At least three people have died and thousands more were rescued after "historic" flooding swamped parts of Louisiana.
Emergency crews plucked motorists from cars stranded by high water along a seven-mile stretch of the south Louisiana interstate, pulled others from inundated homes and waist-deep waters and were braced to continue the work on Sunday after conducting at least 2,000 rescues.
Louisiana governor John Bel Edwards declared a state of emergency, calling the floods "unprecedented" and "historic".
He and his family were forced to leave the governor's mansion when chest-high water filled the basement and electricity was shut off.
"That's never happened before," said the governor, whose family relocated to a state police facility in the Baton Rouge area.
The governor toured flood-ravaged areas by helicopter later on Saturday after rivers and creeks burst their banks and warned Louisiana residents it would be too risky to venture out even after the rains start to subside.
In addition to the three confirmed deaths, Mr Edwards said, at least one person is missing.
One of the worries, the governor said, is that as the rain lessens in the coming hours, people will become complacent and feel too at ease in areas where waters may still be rising for several days, getting in cars in areas that could still be dangerous.
"I'm still asking people to be patient. Don't get out and sightsee," Mr Edwards said. "Even when the weather is better, it's not safe."
In one dramatic rescue on Saturday, two men on a boat pulled a woman from a car almost completely underwater, according to video by WAFB. The woman, who's not initially visible on camera, yells from inside the car: "Oh my god, I'm drowning."
One of the rescuers, David Phung, jumps into the water and pulls the woman to safety. She pleads with Phung to get her dog, but he can't find it. After several seconds, Phung takes a deep breath, goes underwater and resurfaces - with the small dog. Both the woman and dog appeared unhurt.
Elsewhere, rescues continued late into the night, including missions by crews in high-water vehicles who pulled motorists from one swamped stretch of Interstate 12 between Baton Rouge and nearby Tangipahoa Parish.
Major Doug Cain, spokesman for the Louisiana State Police, said about 125 vehicles became stranded on the seven-mile stretch, prompting those rescues.
In the Livingston Parish city of Denham Springs, a suburb of Baton Rouge, entire shopping centres were inundated, only roofs of cars peeking above the water. And in many places, the water was still rising, with days expected before rivers were expected to crest.
Livingston parish sheriff Jason Ard said 2,000 people in his parish alone had been rescued, and more people awaited help.
"We haven't been rescuing people. We've been rescuing subdivisions," he said. "It has not stopped at all today."
Beginning on Friday, six to 10 inches of rain fell on parts of Louisiana and several more inches of rain fell on Saturday, according to the National Weather Service. Some areas got even more rain. In a 24-hour period, Baton Rouge had as much as 11ins while one weather observer reported more than 17ins in Livingston.
Forecasters warned portions of central and northern Louisiana could see heavy rain into next week.
Mississippi governor Phil Bryant declared a state of emergency for several counties in his state as it also battled the heavy rainfall.
Numerous rivers in south-east Louisiana and southern Mississippi overflowed with officials still uncertain just how widespread the damage would be.