A powerful line of fast-moving, widespread windstorms known as a "derecho" has ripped through the Midwest, downing trees, flipping semi-trucks and blowing roofs clear off buildings.
"It's known as a long-lasting group of thunderstorms that produces severe wind and wind damage for at least 250 miles," Weather Channel storm specialist Mark Elliot told Inside Edition.
The term comes from the Spanish word meaning "right," "direct," or "straight ahead," according to the National Oceanic and Atmospheric Administration.
Wind speeds were clocked at up to 100 miles per hour in some places, as the rare storm roared 770 miles from South Dakota to Ohio, according to the National Weather Service.
At least 1.2 million customers were left without power because of the storm system, according to the outage tracking site poweroutage.us.
"This derecho was in progress for a little over 12 hours," Elliot said. "In that time frame it touched about nine different states and went roughly 900 miles.
Derechos are mostly associated with hot and humid weather and curved bands of showers or thunderstorms called "bow echoes," according to NOAA.