UPDATE  8:10 pm. Roughly 10,000 McLean residents are without power, according to the Dominion Power website.

The largest outages are along Kirby Road just between Old Dominion and Westmoreland; west of Georgetown Pike near Langley High School and on the Arlington County line just north of Williamsburg.

The rest of the outages appear to be concentrated between Chain Bridge Road and the Beltway along Old Dominion Drive.

Dominion Power has no estimate of when power will be restored.

UPDATE 7:45pm. Here are several updates:  Nearly 200,000  Dominion customers  are without power, according to a report issued about an hour ago by the Fairfax County Office of Emergency Management.

 9-1-1 service is now partially restored to Fairfax County. If you cannot get through, call 703-691-7561 or 703-691-3680, or report emergencies at closest fire/ police station.

Much of McLean remains without power. There is a gas line at one of the downtown service centers.

Neighbors are heading for hotels. "It was so hot in our home at 3:30am that my husband and I realized we could not stay at home because I am disabled," wrote McLean resident Judy Hasson.

"We started calling hotels but could not get through. We woke up our
son in Indiana who managed to get through and book us into an Embassy
Suites in Alexandria where we are now sitting in an a/c suite waiting
out the blackout."

Del. Barbara Comstock recommended : Remember WTOP 103.5 FM is a great resource for the most up to date information about the situation from all sources -- local and state. (McLean Patch agrees.)

Take safety precautions if using a generator. Do not use a generator indoors. 

Primary hazards to avoid are carbon monoxide poisoning from the toxic engine exhaust, electric shock or electrocution and fire.   More tips here.

Hospitals in Fairfax County are fully-operational on system power and reporting no issues.  Most are having issues with communications (mainly phones), the county reported.

UPDATE 1:15p.m. Dominion Power says that McLean along with Great Falls, Reston and Herndon suffered major hits during last night's storm.

They are still accessing damage and may be a day or day before they can even estimate restoration times.

Giant and McLean Safeway are open. The Anderson Road Safeway is closed.

Also there seems to be no Verizon wireless or ATT service. We have to leave McLean before our IPhone would work.

Crews are working in downtown to restore signal lights. Most major signal lights are working in downtown McLean and in Tysons Corner.

But there are no signals along Dolley Madison Boulevard between McLean and Tysons Corner. There was an accident there at Anderson Road about noon that backed up traffic.

Tysons Corner Mall is open and it's cool.

UPDATE 10 am.More than 300,000 Dominion Power customers in Fairfax are without power including much of McLean.

Dominion Power reports on its website that an estimated 318,000 customers are without power. The company has nearly 400,000 in the county.

Much of McLean is without power including downtown, the McLean District Police station and most street lights.

In driving around this morning from McLean to Tysons Corner, we found only one working traffic signal - at Great Falls and Dolley Madison Boulevard. That signal was working from a generator.

"The power went out at 10:30 pm last night and I just waited an hour for coffee," said Jay Morse, of McLean who has just finished standing in a long line at the downtown McLean Giant.

He said he and his wife had already made reservations at a hotel for tonight.

Good idea because temperatures are fore-casted to soar again tonight with more storms expected. An excessive heat warning is also in effect for McLean and the Washington area.

"It the lack of coffee that's the worst thing," said Neil Dumas, of McLean, who clutched his cup of Starbucks just purchased from the Giant.

Dominion Power says they have no restoration times as of yet.

Tips from Dominion Power on what to do before power is restored:

If electricity has been interrupted:

• Turn off major appliances such as heat pumps, water heaters and stoves. Unplug other appliances such as TVs, stereos, microwaves and computers. This will prevent damage to appliances and possible overloads to the company's system when power is restored.
• Listen to your local radio station on your car or battery-powered radio for regular news and weather updates. Don't rely on your neighbors to report your outage. Call Dominion at 1-866-DOM-HELP (1-866-366-4357).
• Post a list of contents on your freezer door to minimize the number of times you open it.
• Leave one lamp or light on so you will be able to recognize when power is restored.
• If using portable or camp-type stoves or lanterns for cooking and lighting, ensure that the area is adequately ventilated.
• Stay away from fallen wires, flooded areas and debris. Treat all fallen wires and anything touching them as though they are energized.
• Follow safe operating procedures for generators. Never operate one inside your home or in an enclosed space, such as a garage.
• Plugging a generator into a regular household outlet can energize "dead" power lines and injure neighbors or utility workers. Customers should connect individual appliances that have their outdoor-rated power cords directly to the receptacle outlet of the generator, or connect these cord-connected appliances to the generator with the appropriate outdoor-rated power cord having a sufficient wire gauge to handle the electrical load.
• Exhaust fumes contain carbon monoxide and can be deadly, so run your generator outside with proper ventilation. Store the fuel for your generator safely.
• Visually inspect the area around your electricity meter. If you detect or suspect any damage, call us at 1-866-DOM-HELP.