More than 4,100 without power in Washington , utilities say . More than 729,000 flights are canceled for days . All federal offices in Southeast are shuttered , officials say . Casualty toll from storm climbs to at least 10 .
More than 729,000 without power in Southeast , utilities say . More than 4,100 flights are canceled for Thursday . All federal offices in Washington are shuttered , officials say . Casualty toll from storm climbs to at least 10 .