Heavy thunderstorms have caused flash flooding in the Las Vegas area .
Intense rains flooded washes, delayed flights, snarled traffic and prompted several helicopter rescues of people stranded in vehicles in water-filled intersections.
Television news video showed yellow school buses inching slowly along roads after school in areas east of downtown Las Vegas. Muddy brown water reached the lower sills of picture windows of stucco homes in other neighborhoods.
The National Weather Service said more than 1.75 inches of rain fell in downtown Las Vegas.
The Las Vegas area is crisscrossed with miles of concrete-lined flood control channels connected to lake-sized water retention basins.