More rain hits already soaked Louisiana
Further rain has hit an already inundated Louisiana in the US, where flooding in some places was up to the rooftops.
In other areas cars were submerged and families stranded by the floods.
Three people drowned in Oklahoma, Texas and Louisiana.
In Bienville Parish, authorities said a man died and a woman was being treated for injuries after their car was swept off a flooded Louisiana road and into a creek.
In rural south-eastern Oklahoma, a 30-year-old man drowned on Tuesday night after trying to drive his SUV across a low-crossing bridge covered by floodwater.
In Texas, a 22-year-old man drowned after his canoe capsized in Dickinson Bayou, south-east of Houston, near Galveston Bay.
The forecast is for the rain to end by Friday afternoon. Flash flood watches remain in effect for areas from Port O'Connor, Texas, to near Springfield, Illinois.
Drew Scott and another military friend brought in a boat to help evacuate up to 200 mobile homes in the Pecan Valley Estates community in Bossier Parish. Mr Scott said he had gone in his truck earlier to pick up his in-laws but could not get into the park.
"Water, coming up from the Flat River, was waist deep or higher and going into the houses. There were lots of cars flooded out. At the deepest point, I'd say, it was up to my chest and I'm six feet," he said.
Mr Scott said he and his friend assisted the sheriff's office, firefighters and others in getting those who were stranded out of harm's way.
"When things like this happen, people start helping others and that helps restore faith in the country and humanity," he said. "That's the way I was raised and the way I raise my family. I would hope that if the shoe was on the other foot and I needed help that someone would do the same for me."
Sharon Anderson, her three children and four grandchildren were rescued from her Bossier Parish mobile home after rising water threatened to trap them. Several other families already had been trapped, and the water was still rising, she said.
"This morning it was touching the bottom of the houses," she said. "Now the steps on my back porch are under water, and if you walk down the driveway, it's over the knee."
Mrs Anderson said they were pretty much surrounded by the water. The road into the area is flooded and another outlet that has a bridge is closed because of water.
"We're literally trapped," she said. "You have to get a boat to get to our doors in this neighbourhood."
Several Louisiana parishes have declared a state of emergency, and the National Guard was sent in to help.
By Thursday morning, officials in north Louisiana had evacuated 3,500 homes in Bossier City as a precaution as Red Chute Bayou approached the top of its levee.
National Weather Service meteorologist Jason Hansford said the bayou may top the levee or be breached.
Mr Hansford said heavy rain continued across much of north Louisiana on Wednesday night and early Thursday morning with another three inches.
He said a weather spotter just north of Monroe reported 18.1in of rain since Tuesday night.