Update July 1, 7:00 a.m.:
Power outage numbers continue to slowly decrease. As of 6:55 a.m., 293,871 Dominion Virginia Power customers in Northern Virginia are still without power and air conditioning.
"Crews continue to work around the clock to get you back on. It's going to be another hot one, so please be safe," Dominion tweeted at 6:47 a.m. A few minutes later, they tweeted, "Stay tuned. We will be posting work locations later this AM. Will indicate where our crews will be focusing work for today."
In Prince William County, 11,383 Dominion customers are still without power.
This is the last update on this link. For the rest of the July 1 updates, visit .
Update 11:26 p.m.:
Dominion Virginia Power will be reassessing in the morning to see when the entire restoration process will be completed. See the above video for more information.
"Our crews cont'd to assess & uncover storm damage today/evening, we are going to evaluate what they found overnight. Still too soon for estimated restoration times," Dominion tweeted at 11:23 p.m.
Update 9 p.m.:
Dominion Power tweeted "As the cell phone lines open up in Northern Va, more folks are able to report their outages-increasing the stats," at 6:45 p.m.
The power company also alerted that if you get a call back asking if your power is on and it is not to select option 3, which lets the company know there is additional damage to repair. If you hang up, the company assumes you are back on the grid.
As of 8:45 p.m. Saturday, 350,195 Northern Virginia Dominion customers were without power. In Prince William County, 14,312 Dominion customers are still without power.
NOVEC's outage map is reporting 3,839 PWC customers are in the dark. In Manassas Park, 376 customers are without power and air conditioning.
So far, severe thunderstorms have not hit the area this evening. But rain and lightning could be heavy at some points this evening as rain rolls through again.
Update 6 p.m.:
Hang in there! Power outage numbers are decreasing. Dominion reports that 369,231 Northern Virginians are without power.
Dominion's interactive outage map shows that 13,598 Prince William County residents are without power.
without power in PWC as of 5:45 p.m. There are 503 Manassas Park NOVEC customers without power.
Cell phone service has started to return to the area, slowly but surely.
Update 3:22 p.m.: Prince William County has opened cooling centers at and Battlefield High School. Freedom (15201 Neabsco Mills Rd., Woodbridge) will serve as a cooling center from 4-7 p.m.
Battlefield (15000 Graduation Dr., Haymarket, VA) is currently open and will remain open until 7 p.m.
The county posted on its Facebook page that communication center for 911 calls is working intermittently.
As of 3:30 p.m., Dominion Virginia Power reported 396,165 customers without power in Northern Virginia. The temperature at 3 p.m. in Northern Virginia is 100 degrees, according to the National Weather Service.
NOVEC reported 5,899 Prince William Customers without power; 299 Manassas Park residents without power.
Dominion's interactive outage map shows 15,064 Prince William County residents without power.
The Lake Ridge Parks and Recreation Association posted photos on its Facebook page to show extensive damage at the Tall Oaks Pool this morning.
Update 11:45 a.m.
As of 11:43 a.m., Dominion Virginia Power reported still nearly 430,000 customers without power on what could be one of the hottest days this year. Dominion is continuing to ask customers to call by calling 866-DOM-HELP (866-366-4357), or by visiting the Dominion Storm Center, even if you think your neighbor has already reported it.
Other power providers, including NOVEC and Pepco, are also reporting widespread outages.
Many mobile customers of Verizon, AT&T and other major cellular providers are reporting difficulty accessing the Internet, email and making phone calls this morning.
The Fairfax County emergency blog is reporting the county's 911 call center is down. Some areas of Prince William County are also experiencing intermittent difficulties.
An increasing area of concern for emergency officials is the rapidly rising temperature. They are asking residents to check on elderly neighbors and try to stay cool by going to places that do have power and air conditioning — check your local movie theater, mall or library.
Update, 10:12 a.m.:
Verizon and AT&T customers have reported being without cell and home phone service Saturday.
"The severe storms that hit the Washington metropolitan area Friday night – and the resulting power outages that have affected much of the region – have also affected services for some Verizon customers," said Harry J. Mitchell with Verizon Communications. "Our operations teams currently are assessing the impact and are working to restore service as quickly as possible."
Patch is waiting on information from AT&T regarding outages.
UPDATE, 8:49 a.m.:
Prince William County police's communications center is currently unable to accept 911 calls. Call the non-emergency number at 703-792-6500 instead.
Northern Virginia woke up to power outages and scattered tree limbs and debris in roads after a powerful storm hit the area Friday night, killing two people in its wake after a day of record heat.
Khiet Nguyen, 27, of Burke died at about 11 p.m. after a tree hit his 1998 Mercury while he was driving west on Old Keene Mill Drive near Bauer Drive, according to Fairfax County Police. He was pronounced dead at the scene.
A 90-year-old woman died in Springfield when a tree fell on her home as she was lying in bed, according to FCPD. Another occupant of the home called 911 but was unable to reach the victim.
Police, fire and rescue units responded to the home in the 8100 block of Carr Street in Springfield Friday just before 11 p.m. A construction crane and specialized tree removal equipment have been brought to the scene and the operation is ongoing.
The victim’s name will be released when next of kin has been notified.
According to some local meterologists, Friday night's storm may have been a "derecho."
A derecho is "widespread, long-lived wind storm that is associated with a band of rapidly moving showers or thunderstorms. Although a derecho can produce destruction similar to that of tornadoes, the damage typically is directed in one direction along a relatively straight swath. As a result, the term 'straight-line wind damage" sometimes is used to describe derecho damage,'" according to the National Oceanic and Atmospheric Administration (NOAA).
As of 7:30 a.m. on Saturday, the number out of power in the Northern Virginia area was about 450,000 according to Dominion Power spokeswoman Le-Ha Anderson, who was on her way back into the office at about 7:45 a.m. Saturday after a long night updating the media.
"If you experience an outage, it is important that you report it. We will not know your power is out unless you tell us," said a Dominion Power alert on its website. "Every call to our hotline allows our system to narrow down the precise location of the outage so that we can quickly and safely get our crews to the right sites. Also report hazardous or emergency situations by phone."
Call 1-866-366-4357 to report an outage to Dominion.
"It's way too soon to say when power will be restored," said Anderson, adding she expects it to be "multiple days" before power is fully restored to all homes. "Today we're focusing on assessing the damage."
NOVEC said crews are currently responding to outages caused by the severe storms. "If your power is out please call 1-888-335-0500 to report it. Due to the scope of the damage, restoration times may be longer than anticipated."
As of 1:30 a.m. Saturday, outage figures from Domion Power:
Northern Virginia: 462,940
Fairfax County: 242,750
City of Fairfax: 9,000
Falls Church: About 4,700
Prince William County: 22,000
Loudoun County: 36,117
Outage figures from NOVEC (as of 8:20 a.m.):
Prince William County: 8,557
Manassas Park: 772
Were you surprised by the severity of this storm? What were you doing when the derecho hit the area? Tell us in the Comments.
Patch editors Jason Spencer and Lauren Jost contributed to this story.