Donald Wooten had just let his 14-year-old son out the front door of his Fairfax County warehouse early Tuesday morning when, for some reason, his attention was drawn back outside.

"I saw Bub his son standing outside with a terrified look on his face," recalls Wooten, 37, who was carrying a gun because he was counting cash receipts from a three-day sale. "And then someone jumped in front of the glass door, holding a gun in both hands and . . . pointing it right at me. He said, 'Come out of there.'

"That's when I must have shot him," Wooten says, "and then someone shot me."

Yesterday, the Merrifield businessman lay in Fairfax Hospital recovering from a gunshot wound to his right arm that he says has doomed him to a year's worth of physical rehabilitation. Yet Wooten, it turns out, was not the victim of a robbery attempt but of mistaken identity -- as was the undercover police officer who leaped in front of him.

Law enforcement specialists say it is the sort of incident that dramatically demonstrates the hazards--to citizen and policeman alike--of undercover police duty. But the specialists and others note that it also shows that there is little anyone can do to minimize those hazards in extraordinary situations where codes governing police behavior--so as to protect the public--are not always helpful.

"Most of it undercover work really has to boil down to a policeman's judgment and experience," says Fairfax County police spokesman Warren Carmichael, who says his agency does not dispute the basic facts surrounding the Merrifield shooting. "I don't know how you could write a regulation that would govern all undercover situations."

In Tuesday's incident, officers Terry L. Knicely, 27, and Chris D. Carley, 22, had been detailed to watch the Merrifield area because of a recent rash of burglaries and larcenies there, Carmichael says. Dressed in casual clothes and driving an unmarked car, they had been attracted to Wooten's store because there was activity inside, something Carmichael says the officers believed was unusual for 3 a.m.

Inside, Wooten was counting receipts with the help of his sister while his 16-year-old daughter dozed on a nearby couch. Wooten says he had just let an armed guard go home -- "I'd kept him longer than I'd said I would" -- and had agreed to let his son get some coffee from a nearby store.

Apparently just as the two policemen were closing in on the store, Wooten opened the glass front door to his warehouse, at 2832-A Dorr St., so his son could leave and then closed it behind him.

"I was just sitting on my moped when two guys came around the corner with guns drawn," says Donald Jr. "They said, 'Stop--Police!' "

His father, inside the building, says he heard nothing, but when he turned around and was confronted by an armed man, his fears of being robbed seemed to be coming true.

"I knew I'd hit him," says Wooten of his only gunshot. "I thought maybe in the chest . . . I hollared to my son, 'Run, Donald, Run,' as soon as I shot. One second later, two seconds later, I got hit. I heard five or six shots. There was terrible pain, blood gushing. They kept shooting."

Wooten staggered back inside his office where his hysterical sister handed him another gun. "She was screaming, 'Oh, my God! What are we going to do. They're going to come in and get us.' "

Feeling himself growing weak from blood loss--an artery had been hit--Wooten nonetheless struggled out of the office.

"One of them was standing there with a gun," recalls Wooten. "He said, 'We're the poh-lice!' I said, 'Please show me a badge, my God, a badge.' "

The officer did, says Wooten who then slumped to the ground in agony. Also wounded in the shooting was Knicely, who has since been discharged from Fairfax Hospital.

While he noted that he had no direct knowledge of the case, Bill Nash, an official with the International Association of Chiefs of Police in Gaithersburg, says that it appeared the Fairfax officers may have handled the situation properly.

"They identified themselves, but it looks like the father didn't hear," he says. "It's one of those things that no police policy can address, really."

Even so, he says, there are things that both the businessman and the police department could have done that might have headed off the incident before it ever occurred.

In many Wisconsin communities, he says, "store owners contact police and advise them if they're working in their businesses after hours." By the same token, he says, "it is incumbent on a police chief to inform the public of any type of enforcement detail" underway in their area.

Carmichael, who noted the incident is under investigation, says that it is often impossible to inform the public of every move the department makes, in part because of geographical concerns but also because plainclothes operations are designed to apprehend criminals in the act "and we'd be tipping our hand."

Nash, however, disagrees.

"The object," he counters, "is not to apprehend criminals in the act, but to keep them from committing crimes. If the thief doesn't know who is a police officer, that's a deterrent, too."