Across the US, a day of extreme weather prompts heat warnings, severe flooding and power outages for hundreds of thousands

In a matter of hours Monday, the iconic landmarks of Yellowstone National Park were shuttered to the public and its roads left unpassable after a torrential downpour and rapid snowmelt contributed to unprecedented flooding at one of America's most visited national parks.

A helicopter flying overhead captured scenes of destruction -- with massive chunks of concrete snatched from the road as the swollen Gardner River raged outside its banks. It was one of many scenes of extreme weather Monday across the US.

In a span of 24 hours, American communities grappled with a slew of severe weather threats that left hundreds of thousands without power in the Midwest, trapped flooded communities in Montana without clean drinking water, prompted tornado warnings in Chicago and left millions battling sweltering heat.