The storm weakened from a hurricane as it moved over land, forecasters said, but it still posed risks and a flash flood emergency was earlier issued for the city of New Orleans.

Local TV stations and footage on social media showed coastal towns battered by the storm, with some streets flooded and locals filling sandbags to protect property from floodwaters.

More than 370,000 customers across Louisiana were without power, according to monitoring website poweroutage.us.

Francine made landfall as a Category 2 hurricane on a five-level scale in Terrebonne Parish, on the southern edge of the state, at 5:00 pm local time (2200 GMT), according to the National Hurricane Center (NHC).

Hours later Francine was downgraded to a tropical storm with sustained winds of 50 miles (85 kilometers) per hour, with three to six feet (one to two meters) of storm surge, and up to a foot of rain in some parts of Louisiana, as well as areas of Mississippi, Alabama and the Florida panhandle, the NHC added.

"This rainfall could lead to considerable flash, urban, and river flooding," the NHC said in a bulletin at 0600 GMT.