WASHINGTON (NEXSTAR) — Search and rescue efforts are underway as more than a million customers remain without power in Louisiana.

The damage is still being assessed, but Federal Emergency Management Agency officials say they are on the ground helping victims trying to pick up the pieces.

Sen. Bill Cassidy, R-La., says evacuated residents should not return until water subsides and power is restored.

“They’ve been hammered,” Cassidy said. “They won’t recover until they get power back.”

Cassidy surveyed the damage from a Coast Guard airplane Monday. He expects a long recovery.

“That flooding may take a while to resolve or even worsen over the next couple of days,” Cassidy said.

But Cassidy says because of post-Hurricane Katrina infrastructure improvements, some areas were protected.

“Preparation works,” Cassidy said.

Right now, the President Joe Biden administration is rushing resources to the area, including sending thousands of National Guard troops to help with search and rescue.

“We know that a lot of people evacuated but unfortunately, a lot of people could not,” Marcus Coleman with FEMA said.

Coleman says FEMA has thousands of employees on the ground and is working side by side with dozens of nonprofits.

“To make sure any immediate needs are met and that people know that they can start the process of applying for individual assistance,” Coleman said.

Jason Keeling with the American Red Cross says his organization is providing shelter to more than 2,500 people across the Gulf Coast, and he expects that number to rise.

“We do anticipate that it could be a long haul, particularly given the power outages,” Keeling said. “But we’re prepared for however long the need exists.”

Keeling says more Red Cross officials are being deployed to help victims seeking shelters.

Even as shelters fill, Keeling says COVID-19 social distancing guidelines will be enforced.