Heavy rain caused dangerous flash flooding and the flash flood watch was extended until 2 p.m. on Monday. National Weather Service meteorologist Cody Ledbetter said the storm dumped about 6.3 inches of rain near Frederick, Maryland, about 4.5 inches near Arlington, Virginia, and about 3.4 inches at Ronald Reagan Washington National Airport in a two-hour period.
Frederick police are warning drivers to be cautious even after the water recedes as there may be debris left behind on the roads.
The heavy rain paralyzed cars on washed-out roads. Images posted to social media showed drivers stranded in the floodwaters.
One video taken captured a rush of water breaking down from the surface and penetrating the concrete ceiling at the Virginia Square metro station in Arlington, Virginia.