A teen-aged clerk was shot yesterday in a Baileys Crossroads record store by a man who then turned the handgun on himself, according to Fairfax County police.

Police said 16-year-old Katherine Painter of 3458 S. Wakefield St. in Arlington was taken to Fairfax Hospital where she was listed in serious condition last night with a head wound. Clarence James Allen Jr., 43, of the same address, also was taken to the hospital with a head wound, said police spokesman Warren Carmichael. Allen was in critical condition and on a life-support system, according to a hospital official.

Painter was working at the cash register of Kemp Mill Record Shop, 5851 Leesburg Pike, when a man entered the store about 3:20 p.m., according to store manager Barry Jones. Jones, who was shelving records at the time, said he heard something "that sounded like a firecracker" above the music playing from the store's loudspeakers.

Jones said he then saw Painter struggling with the man, and when she fell to the floor, he shot her and then himself in the presence of about six customers. "Everyone was in shock," Jones said. "It was the worst trip I've had."

Painter was rushed to Fairfax Hospital by helicopter. Allen was taken there by ambulance.

Carmichael said he did not know the motive in the assault but said police believed they were dealing with "what appears to be a domestic situation." He said no charges have been filed in the shooting.

Carmichael said the man drove up to the store in a blue hatchback Mazda with Maryland license plates and left the motor running while he entered the store with a handgun.

The car has decals from American University, the U.S. Coast Guard Academy and Georgetown University, according to witnesses.

Jones described Painter as "your average girl next door" who talked about her boyfriends and football games and worried about looking fat even though she was "thin as a rail." He said she had worked at the shop on weekends for about two years. Employes in nearby shops said Painter recently got her driver's license.

The Kemp Mill Record Shop is in a small shopping center on the west side of Leesburg Pike.