Hurricane Ida has pounded Louisiana, flooding wide areas, plunging 1million New Orleans homes into darkness and reversing the flow of the Mississippi.
A 60-year-old man killed by a tree falling on his house near Baton Rouge was the first fatality of the hurricane.
It blew in from the Gulf of Mexico with 150mph winds, exactly 16 years after Hurricane Katrina battered the coast, claiming 1,800 lives.
President Joe Biden declared a major disaster in Louisiana, ordering federal assistance to bolster recovery efforts.
Nearly all offshore Gulf oil production had been suspended ahead of the storm and residents of the most vulnerable coastal areas evacuated.
But power to more than 1million homes and businesses in New Orleans was knocked out on Sunday after transmission lines to the city failed.
One transmission tower collapsed into the Mississippi, which saw its flow briefly reversed on Sunday as Ida roared in.
Residents in Louisiana have now reported cases of looting after the hurricane first hit.
Several men were pictured trying to rob a cash machine in a market in New Orleans neighbourhood St Claude, while in New Orleans East a group was pictured looting a store.
Mayor LaToya Cantrell said that local police are cracking down on looting and anyone caught doing so will be charged with a state felony.
She said: ‘My directive has been very clear: lock ’em up. We will not tolerate and we have not tolerated it.’
However she said that the looting isn’t as widespread as it appears.
She added: ‘There is no widespread looting going on in the city of New Orleans.
‘What we do have that’s widespread are residents who are being neighbors, who are understand and exhibiting the spirit of humility, of empathy, who are cleaning up their lawns and who are servicing their community.
‘That’s widespread in the city of New Orleans, that’s who we are.’