tropical storm
The vehicles are believed to have hydroplaned as Tropical Depression Claudette swept across the southeast. Nine of those killed were children, authorities said.
The impending storm forced postponement of weekend Juneteenth celebrations in Mississippi and Alabama.
The storm has left scores of people dead and over 100 others missing in Mexico and Central America after it made landfall as a category 4 hurricane.
Beta was brewing in the Gulf of Mexico, 205 miles southeast of Galveston, Texas, the U.S. National Hurricane Center said Sunday morning.
WHAT'S HAPPENING
It could be the first time two hurricanes form in the Gulf of Mexico simultaneously, according to records dating to at least 1900.
Tropical Storms Laura and Marco were both projected to approach the U.S. Gulf Coast at or near hurricane force.
At least nine people were killed, including a 5-year-old girl, and millions of others were left without power.
Millions of people were without power on Wednesday after felled trees downed power lines.
Roads flooded in coastal Louisiana and Mississippi, and thousands were without power even before the the storm made landfall.
Bertha's maximum sustained winds were near 50 mph as it came ashore but it was expected to weaken to a tropical depression after moving inland.