Louisiana residents were ordered on Sunday to evacuate low-lying coastal areas as back-to-back hurricanes were forecast to bring strong winds and rain.
Tropical Storm Marco, which is forecast to hit the Louisiana coast with hurricane-force winds on Monday, will be followed by Storm Laura on Thursday.
Twin hurricanes arriving at the US coast within days "could result in a prolonged period of hazardous weather," National Hurricane Centre forecaster Stacy Stewart warned on Sunday.
Officials in Louisiana's coastal Lafourche Parish ordered a mandatory evacuation for residents of low-lying areas at noon on Sunday. The US Coast Guard also raised its warning for the Port of New Orleans, calling for ships to make plans to evacuate some areas.
The potential for flooding and evacuations added to worries about the spread of COVID-19.
In Grand Isle, at the state's southern tip, authorities were placing sandbags to bolster its protective levy while energy companies continued to pull workers from offshore platforms and shut production in the US Gulf of Mexico wells.
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