At least seven persons were injured last night when high winds spawned by a severe thunderstorm tore into a 12-story apartment building in Fairfax County, shattering windows, bending iron balcony railings and scattering household items from several of the apartments onto the ground below.

About 30 persons were left homeless by the early-evening storm, which laced Northern Virginia for about 10 minutes with an inch and a half of driving rain and wind gusts measured at up to 64 miles an hour at National Airport. An official of the Red Cross said those who could not return to their apartments would be temporarily sheltered in area motels.

Only two of the injured required hospitalization. They were identified as Heidi Jones, 30, and Tracey Ann O'Donnell, 21, both residents of the damaged building, the Cavalier Club Apartments at 6200 Wilson Blvd. Both were reported in fair condition at Fairfax Hospital last night after being treated for arm and leg cuts.

Fairfax County fire officials said last night that about 15 apartments in the northeast wing of the butter-colored brick complex were damaged, but no estimate of the extent of the damage was immediately available.

About 10,000 Virginia Electric and Power Co. customers in Northern Virginia were left without electricity as a result of the storm, according to a Vepco official. Repairmen were working into the night to restore power.

Arlington County police also reported that windows in several businesses in the 3100 block of Wilson Blvd. were smashed by high winds as the storm moved eastward.

The National Weather Service issued a severe thunderstorm warning for Alexandria, eastern Fairfax County, the District, southern Prince George's County and Charles County at 7 p.m., but the winds apparently died down as the storm ran its course, and the warning was canceled a short time later. No damage was reported outside Northern Virginia.

Several hours after the storm, workmen and firefighters labored to clean up the debris left strewn around the apartment building. Shards of glass and pieces of the building's rooftop air-conditioning unit littered the ground. At least 60 autos in the apartment's parking lot also were reported damaged.

On the upper floors of the building, furniture and window frames lay on the twisted remains of the wrought iron and concrete balconies.

"My apartment was shaking like it was an earthquake or something," said fourth-floor resident David Salem of the effects of the storm. His apartment was not damaged.