(NEW YORK) -- Nearly two million people are still without power in several Midwest and mid-Atlantic states that were pummeled by a series of violent thunderstorms last Friday night.
That number includes more than half a million homeowners in Washington, D.C., who have been told they may not get their power back until the end of the week.
D.C.’s power company, Pepco, says utility crews are working hard, removing hundreds of downed trees and re-stringing countless power lines. Pepco spokesman Clay Anderson says utility crews from as far away as Canada have been called in to help restore power.
All told, about three million homes lost power, and 22 people lost their lives. The governors of Ohio, West Virginia, Maryland and Virginia, and the mayor of Washington, D.C., all declared states of emergency.
Meteorologists say the lightning, fierce winds and pounding rain that pummeled the region was not your average series of thunderstorms, it was a “derecho.”
AccuWeather meteorologist Brian Edwards says a derecho forms when an atmospheric disturbance lifts warm air in regions experiencing intense heat, causing thunderstorms and hurricane-force winds to develop. The region had experienced several days of 100-plus temperatures ahead of last Friday’s storms.
Friday's derecho took 12 hours to cover more than 700 miles before reaching the Atlantic Ocean.
Edwards says derechos are more difficult to predict than other severe weather events because meteorologists are unable to identify exactly where the precise combination of factors needed to trigger a derecho will emerge.
Copyright 2012 ABC News Radio