More than 7,000 people had to be rescued from flood waters in the southern US state of Louisiana, Governor John Bel Edwards said Sunday.
Four people have been confirmed dead and officials warned residents to remain cautious as rivers continued to crest despite improving weather conditions.
State police said they were still working to reach motorists stranded along a major highway, and hundreds of roads remained closed.
The state had requested federal disaster assistance, Edwards said.
"This is no time to let the guard down," he told a press conference, asking residents not to "go out and sight-see."
US President Barack Obama issued an emergency declaration to free federal funds for disaster assistance, and told Edwards in a phone call late Sunday that the US government would help in recovery efforts, the White House said.
The flooding began Friday after rainfall battered an area in the southern part of the state near the capital Baton Rouge.
The National Weather Service said flash floods could occur along the US Gulf Coast in Texas and Louisiana, as well as further north in the central US.