WASHINGTON (AP) — At least two people have died, thousands of U.S. flights have been canceled and more than 1 million have lost power as destructively strong storms move through the eastern U.S. Residents were warned to stay indoors Monday and prepare for the worst. The threat of severe thunderstorms and tornados stretched from Alabama to New York. Officials say a 15-year-old boy was killed by a falling tree in South Carolina and a 28-year-old man was killed by lightning in Alabama. Homes and businesses in nearly a dozen states lost power as trees and power lines fell onto roads and homes. FlightAware says more than 2,600 U.S. flights have been canceled and nearly 7,900 delayed.