UPDATE (6:20 p.m.) Power is back on at 's Fairfax campus.

(5:37 p.m.) Now about 800 customers without power according to Dominion. (5:12 p.m.) Add your storm photos and videos to this article or email to whitney@patch.com.

(4:53 p.m.): 's Fairfax campus is experiencing power outages. Call Mason Police at 703-993-2810 if you need help. (4:13 p.m.): Dominion Power reports just under 600 customers without power in Fairfax City. Click here to see outages in your neighborhood.

(4:09 p.m.): Now back to a thunderstorm warning. Reports suggest tornado spotted near #Fairfax moving east. Warning done for #Fairfax, but NE still in effect. Follow @FairfaxPatch on Twitter for more updates. (3:39 p.m.) Tornado Warning in effect until 4 p.m. Take cover.

(3:20 p.m.): Watch upgraded to a warning until 4:30 p.m. From Fairfax County EMAS:

"The National Weather Service indicates the storm is expected to enter Fairfax County at 3:30PM with 60-70MPH Winds. Expected to cross through Fairfax City at 3:45. Rainfall could be up to 1"-1.5"."

National Weather Service issued a severe thunderstorm watch until 10 tonight. Move indoors and stay away from windows to escape hail, damaging gusts and cloud to ground lightning.