James L. Kolstad's wife recalls her husband awakening one night this month, fearful that he had heard a pistol shot outside their Fairfax County home.

But Kolstad, certain his mind was playing tricks on him, rolled over in his bed and went back to sleep, unaware that he like 18 residents of the fashionable Fort Hunt subdivision had become victims of vandals who for three nights quietly rode through the tree-lined neighborhood shooting aimlessly at parked cars.

Firing a 9-mm pistol, they left 20 cars punctured with dime-sized holes. A 1972 Thunderbird on Karl Road, a 1974 Vega on Bainbridge Road, a 1972 Volkswagen on Parry Lane, Kolstad's 1975 Dodge camper on Courtland Road were among the targets. Cartridge casings were found in the streets.

In all, damage to the cars totalled "$30,000 at a bare minimum," police Cpl. Paul Crovato said yesterday. Some cars were hit as many as nine times, the bullets hitting electrical systems, radiators and engines. One Corvette, a fiberglass-body sports car, had $2,500 worth of damage, Crovato said.

But like virtually all of the 9,494 cases of vandalism reported to Fairfax police last year, Cravato and other officers are at a loss to offer a motive for the crimes. "They must have done it for a lark . . . Perhaps to hear the gun go off . . . There was no malicious intent to single out anyone," he said.

If there is a difference in the Fort Hunt crimes and most other acts of vandalism, it is that a police inspector spent 26 straight hours on the case and in the early-morning hours after the third night of shooting arrested two college students.

The students, one the son of a member of the Federal Communications Commission, were charged with 19 counts of damaging personal property. Each count is a class-one misdemeanor under Virginia law carrying a maximum of a $1,000 fine and 12 months in jail.

Such arrests, however, are as rare as acts of vandalism are frequent in suburban Washington, police said.Troubled by the "very, very small" percentage of arrests, Fairfax police recently targeted the crime for higher arrest rates during the coming year.

Even so, officers who specialize in following such crimes in the county said yesterday that the odds favor the vandals. "This is just one of those things," said Cpl. R. D. Allison, an officer assigned to the Mason District, which has been hit hard by vandals in the past.

"Nothing stops it," Allison said. "It is a crime of opportunity," committed most often by youngsters roaming in groups of two or more seeking "something to do."

Vandalism often begins on a dare, he said. The targets, as in the Fort Hunt case, are frequently cars for no other reason than "there are so many of them."

Spectacular as the Fort Hunt case may seem, it is not the biggest case Fairfax police have recently investigated. In October two teenagers were charged in a case in which 102 windshields and one picture window in a home were reported broken with a slingshot.

By yesterday many of the victims of the Fort Hunt vandalism said they had managed to repair their cars, but they still are troubled by the crime. "I don't understand it," said Mrs. Richard F. Johnson, whose 1972 Thunderbird was damaged. "I have a teenaged son, so I asked him point blank. 'Why would anyone want to do this?'"

"And do you know what he said? It was strange. He said it was boredom, sheer boredom."

Neither of the two students charges in the incident could be reached for comment. FCC Commissioner Joseph R. Fogarty, who lives in the Fort Hunt area, declined comment and said he would advise his 19-year-old son, John B. Fogarty of 915 Emerald Dr., Alexandria, to avoid comment also.

Luigi Picciano of 4513 Ferry Landing Rd., Alexandria, whose 20-year-old son Mark was charged in the Fort Hunt vandalism, said "I can't explain it . . . I don't have the solutions."

Vandals once broke out the windows in their former home in Alexandria the elder Picciano said. "I feel just as bad for the victims," he said. If the charges are "proven in court," he said. "I hope we will be given a chance to reconstruct the boy."

"There's no social status" to the crime. Allison said. In Fairfax County, much of the vandalism has occurred in the McLean area and in the Mason district, both largely residential areas, he said. Overall, Fairfax police say an act of vandalism occurs every 1.08 hours, so frequently that police ask victims if they can give a report of the crime by telephone.

Because it's a crime against property and usually occurs at night, witnesses are rare, one fact that makes arrests unlikely.