WASHINGTON - Nearly 4 million homes and businesses were without power on Saturday amid a record heat wave in the eastern United States after deadly thunderstorms downed power lines from Indiana to New Jersey. At least 11 people were killed.

Statewide emergencies were declared in Washington D.C., Ohio, Virginia and West Virginia because of damage from overnight storms, which brought hurricane-force winds along a 500-mile (800km) stretch.

Forecasters predicted more severe thunderstorms as renewed heat blanketed the area on Saturday.

A child looks at a house struck by a tree after a violent thunderstorm ripped through the area on Saturday evening, in Falls Church, Virginia, June 30, 2012. [Photo/Agencies]

Temperatures surpassed 100 Fahrenheit (37 Celsius) in several southern cities, including Atlanta, where the mercury hit 106 degrees (41 C), and Charlotte, North Carolina, where it reached 102 F (38 C), according to Accuweather.com. The nation's capital cooled down to 96 Fahrenheit (96 C).

Restoring power in some areas could take up to a week. Utilities in Ohio and Virginia described damage as catastrophic.

"It's going to be a while before some folks get power, and with the heat, that's our big concern," said Bob Spieldenner, a spokesman for the Virginia Department of Emergency Management.

More than 1 million Virginia customers had no power in the worst outage not linked to a hurricane in the state's history, he said.

Six people were killed in Virginia in storm-related incidents.