Aftermath of Storm Ida in New Orleans

Ida lost some of its punch over southwestern Mississippi on Monday after making landfall in Louisiana as one of the most powerful hurricanes to hit the region, but it could still trigger heavy flooding, the National Hurricane Center said.

Ida, the first major hurricane to strike the United States this year, made landfall around noon on Sunday as a Category 4 storm over Port Fourchon, a hub of the Gulf's offshore oil industry, packing sustained winds of up to 150 miles per hour (240 km per hour).Although weakened to a tropical storm, heavy downpours could bring life-threatening flooding, the NHC said.

Federal Emergency Management Agency (FEMA) administrator Deanne Criswell said the full impact of the storm would become clear later in the day.

"We're hearing about widespread structural damage," Criswell said in an interview with CNN. "I don't think there could have been a worse path for this storm. It's going to have some significant impacts."Federal levees installed to reduce the risk of flooding appeared to have held, according to preliminary reports.