WASHINGTON -- Millions across the mid-Atlantic region sweltered Saturday in the aftermath of violent storms that pummeled the eastern United States with high winds and downed trees, killing at least 13 people and leaving 3 million without power during a triple-digit heat wave.

Power officials said the outages wouldn't be repaired for several days to a week, likening the damage to a serious hurricane. Emergencies were declared in Maryland, West Virginia, Ohio, the District of Columbia and Virginia, where Gov. Bob McDonnell said the state had its largest non-hurricane outage in history, as more storms threatened.

"This is a very dangerous situation," the governor said.

In some Virginia suburbs of Washington, emergency 911 call centers were out of service; residents were told to call local police and fire departments. Huge trees fell across streets in Washington, leaving cars crunched up next to them, and onto the fairway at the AT&T National golf tournament in Maryland.

Cellphone and Internet service was spotty, gas stations shut down, and residents were urged to conserve water until sewage plants returned to power.

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The outages were especially dangerous because they left the region without air conditioning in an oppressive heat. Temperatures soared to highs in the mid-90s in Baltimore and Washington, where it had hit 104 on Friday.

"I've called everybody except for the state police to try to get power going," said Karen Fryer, resident services director at two assisted living facilities in Washington. The facilities had generator power, but needed to go out for portable air conditioning units, and Fryer worried about a few of her 100 residents who needed backup power for portable oxygen.

The storm did damage from Indiana to New Jersey, although the bulk of it was in West Virginia, Washington, and suburban Virginia and Maryland.

At least six of the dead were killed in Virginia, including a 90-year-old woman asleep in bed when a tree slammed into her home. Two young cousins in New Jersey were killed when a tree fell on their tent while camping. Two were killed in Maryland, one in Ohio, one in Kentucky and one in Washington.