A tornado spawned by summer thunderstorms ripped the roof and a wall from a house in Chantilly near Dulles International Airport last night and desposited them 400 feet away against the side of a church.

No one was injured and no one was at home in the house -- a nieghbor said the family was in Virginia Beach for a wedding -- when the twister hit about 7:20 p.m.

The thunderstorms that brought the tornado whipped through the Washington area bringing drenching rains, strong winds and the promise of respite from yesterday's high humidity. They also left nearly 7,000 homes and businesses without electricity.

The storms, which dumped as much as 2 inches of rain in some parts of Northern Virginia, had mostly moved east and out of the area by 9:30, according to meterorologists at the National Weather Service.

The tornado touched down for only a few seconds in Chantilly, removing the roof and one wall from a two-story colonial-style house of the Paul L. Watson family at 13821 Leighfield Rd. and slightly damaging two other homes. Several second-floor rooms of the Watsons' house stood exposed last night. Wreckage was deposited against the side of St. Timothy's Roman Catholic Church 400 feet away. No damage estimates were available last night from Fairfax County fire officials.

The five numbers of the Watson family moved the house only last month, according to neighbors.

Susan Artz, who lives next door at 13189 Leighfield Rd., said she was home with her husband and two children when the tornado struck. "It was like a train sound," she said. "You feel like you're in a big vacuum."

She said that when the noise and wind subsided her family went outdoors and surveyed the damage. In addition to the destruction next door, their own mail box had been ripped out of the ground, cast iron outdoor furniture thrown around the back yard and shingles pulled from the roof.

The Virginia Electric and Power Co. reported that the thunderstorms left 4,000 homes and businesses in Faixfax City, Herndon, Great Falls and Vienna without electricity. The Potomac Electric Power Co. said power outrages affected about 2,700 customers in the Kensington and Norbeck areas of Montgomery County. Both power companies said they expected electricity to be restored by morning.