Young Kyu Kim said he had his finger on the trigger of a shotgun pointed at the head of an alleged intruder in his Fairfax County auto repair shop yesterday when the man's screams for mercy caused him to stop.

Instead, following gunfire and a scuffle in which the intruder nearly broke away, Kim was able to apprehend the would-be burglar, tie him to a chair and call the police.

Police have charged Brian T. Hall, 30, of no fixed address, with breaking and entering.

Kim, the owner of International Auto Service Center on Richmond Highway, said that he had fallen asleep in the office while working on business records when he heard noises coming from the adjacent cashier's room.

Kim, 45, said he then fired five "warning shots" from a .357 magnum handgun he keeps in his office through the office door into the cashier's room.

When he tried to leave his office to investigate, Kim said, the intruder was pushing against the door, making it impossible for him to leave his office.

Although he had already used all the bullets in the handgun, Kim said he then yelled to the intruder that an additional shot would be aimed directly at him if he did not leave.

This threat was followed by a scurrying noise, Kim said, after which he walked into his office and discovered the cash register open.

Carrying a 20-gauge shotgun, Kim then stalked Hall into the body shop of the building, he said.

"It was dark and I didn't know where he was or if he had a weapon," Kim said.

Kim found Hall hiding beneath a car in the body shop, he said.

"I had the shotgun pointed at his head and I was ready to pull the trigger," Kim said, "but then he looked up and yelled 'Please don't shoot,' so I let him get up."

After this, Kim said, the intruder tried to overcome him physically, forcing him to ward him off with the butt of his shotgun.

Kim said he then fired another warning shot and quickly reloaded his shotgun.

Holding Hall at gunpoint, he forced him into a chair in the machine shop, and tied him up with automotive belts, Kim said.

"Then I called police, and they were there right away."

Kim said before police arrived he was startled to see Hall digging into his pocket, thinking that he would produce a weapon. "But he was just getting a cigarette," Kim said.

Kim admitted afterward that he was frightened.

Police said Hall was taken to Mount Vernon Hospital for treatment, where he required eight stitches to close the wound in his head where he had been struck.

Kim said he keeps weapons on hand because his business has been vandalized in the past. The guns are licensed at Kim's Rockville home, he said.

Fairfax County prosecutor Robert F. Horan Jr. was out of town yesterday, and his office declined to comment on whether Kim had violated any laws, pending the review of the case. circumstances of his apprehension of Hall.