A pipe bomb exploded inside a gynecology clinic in the Seven Corners area yesterday evening, causing about $10,000 in damage and knocking down the wife of the physician who operates the clinic, Fairfax County police said. They said four unexploded bombs were found inside.

Police said they had no idea who might have planted the bombs and knew of no motive in the incident at the Arlington-Fairfax Medical Clinic, at 6051A Arlington Blvd. The physician, Dr. Nicolae Filipescu, could not be reached immediately for comment.

The explosion occurred at about 5:30 p.m. in the two-story brick building, in which Dr. Filipescu opened the clinic three months ago.

Filipescu's wife, Louise, entered the clinic at about 5:25 p.m. to do some office work. After finding papers in disarray, police said, she went back to the front door to check for signs of a break-in, and saw smoke coming from a metal container used to store urine samples. She ran out of the building seconds before the blast. Although she was thrown to the ground, police said, she was not seriously injured.

County fire officials said the blast knocked out windows on the first and second floors of the building and started a small fire that caused minor smoke damage.

In addition to county police and fire officials, law enforcement officers and explosives experts from the state police and the federal Bureau of Alcohol, Tobacco and Firearms went to the scene, in a new town house complex near Patrick Henry Drive.

The unexploded bombs were disarmed safely. Police said an investigation is continuing.