Last Update 3:26 p.m. ET
(CBS/AP) Violent storms swept across the eastern U.S., killing at least 12 people and knocking out power to millions of people on a day that temperatures across the region are expected to reach triple-digits.
The Mid-Atlantic region had already been experiencing 100-degree temperatures before Friday evening's violent storms. More than 3 million are without power — and without air conditioning — as crews work to clear downed tree limbs and restore electricity.
The storms were blamed for the deaths of six people in Virginia; two in New Jersey; two in Maryland; one in Ohio; and one in Washington, D.C.
Storms knock out power to 2M in eastern U.S.
In suburban Washington, residents were told to call non-emergency phone numbers or go to fire and police stations if they needed help because even 911 emergency call centers were without electricity.
Power outages were reported from Indiana to New Jersey, with the bulk of the service interruptions concentrated in the Mid-Atlantic region. Earlier Friday, the nation's capital reached 104 degrees — topping a record of 101 set in 1934.
On Saturday, temperatures were expected to reach 100 degrees again — and another round of storms was also possible. The National Weather Service warned the heat index could reach 110 degrees.
The heat left people such as the elderly vulnerable. In Charleston, W.Va., firefighters helped several residents of an apartment building, some using wheelchairs or walkers, move to a shelter. Fire Capt. Chris Campbell said the evacuation was voluntary and was the only one since the storm hit. But he expected more.
More than 20 elderly residents at an apartment home in Indianapolis were displaced when the facility lost power due to a downed tree. Most were bused to a Red Cross facility to spend the night, and others who depend on oxygen assistance were given other accommodations, the fire department said.
Among the fatalities: A 90-year-old Virginia woman asleep in bed when a tree slammed into her home, and two young cousins on a camping trip in southern New Jersey.
Anne Arundel County, Md., police said in a news release Saturday that 25-year-old Kevin Obrien was killed when a tree fell onto his car late Friday. Two other people in the car suffered minor injuries.
In Pittsgrove, N.J., police say two boys, ages 2 and 7, were killed after a tree fell on their tent during the storm early Saturday at Parvin State Park. Authorities say the boys' families had been camping at adjacent sites when the storm hit, and the families decided to huddle together in one tent. They say the heavy winds and rains from the storm snapped a pine tree, which then fell on the families' tent.
The boys suffered serious injuries and died.
Falling tree kills 2 children at N.J. state park
In addition, a park police officer was injured by an uprooted tree in the northern Virginia county, and an 18-year-old man was struck by a power line, Fairfax County police spokeswoman Mary Ann Jennings said.
At least four utility poles fell on a road in Columbus, Ohio, making it too dangerous for people in four cars to get out, police said. One person was taken to a hospital.
Amtrak suspended its service from Washington, D.C., to Philadelphia due to the storms, at least until mid-morning.
"It has had a widespread effect on the region," Metro spokesman Dan Stessel said early Saturday. He said about 17 train stations were operating on backup power due to local power outages, but that he didn't anticipate service being disrupted on Saturday.
Storm damage, including uprooted trees, also delayed the start of third-round play at the AT&T National golf tournament in Bethesda, Md. Spectators and volunteers are being barred from the course Saturday owing to safety concerns.
Storm damage bars golf fans from AT&T National
A line of thunderstorms, 100 miles from tip-to-toe, rolled through the Washington. D.C. area Friday night packing winds of 50-to-80 mph, reports Topper Shutt of CBS D.C. affiliate WUSA-TV. The same clump of storms hit southeastern Ohio and West Virginia with hurricane force winds Friday evening.
These types of storms, known as Musicale Convective System, or Derecho, are usually seen in the Midwest and not in the Mid-Atlantic, Shutt adds.
Power outages

Widespread power outages were reported from Indiana to New Jersey, with the bulk of the service interruptions concentrated on Washington, D.C. and surrounding areas, leaving many without power - and without air conditioning - on a day that temperatures are expected to reach triple digits across the eastern U.S.
No power also meant no way to charge cellphones and laptops, and no Internet access in many areas.
Ohio Gov. John Kasich and West Virginia Gov. Earl Ray Tomblin each declared a state of emergency.
In Ohio state emergency officials say 800,000 to 1 million people still had power outages Saturday morning in the aftermath of severe storms that one utility said were the most powerful, damaging winds since Hurricane Ike's in 2008.
American Electric Power said damaged poles and distribution circuits in Ohio and W.Va. will slow restoration for days.
In New Jersey, more than 96,000 Atlantic City Electric customers and 1,800 Jersey Central Power & Light had no service late Saturday morning, with Atlantic and Cape May counties the hardest-hit areas.
In Maryland BGE is working to restore power to more than 420,000 customers. As of Saturday morning, BGE has restored service to more than 100,000 customers, such the utility says "a large number" of customers should expect to be without power for several days.
In addition to the outages, BGE says it is dealing with the prospect of further storms throughout the weekend and the impact of high temperatures, which creates additional demand.
Record heat

On Friday, the nation's capital reached 104 degrees — topping a record of 101 set in 1934.
On Saturday, temperatures were expected to reach 100 degrees again — and another round of storms was also possible. The National Weather Service warned the heat index could reach 110 degrees.
But by late morning, it was already plenty hot.