In Virginia's hunt country -- the land of sweet grass purebreds and millionaires -- someone came out on a clear moonlit night three weeks ago and shot two gaping holes in the serenity of the rich.

That someone, carrying a high-powered rifle and firing from a paved road three miles north of Middleburg, shot a hollow-point bullet into the neck of a chestnut quarter horse owned by Pamela Harriman, wife of dipolmat Averell Harriman.

Then he -- or she -- turned to another pasture and fired a bullet through the liver of a pregnant, purebred Red Angus cow. The cow, named Elia, was killed instantly. The horse, named Wingrove suffered for four days under the care of a team of veterinarians before it died.

"In horse country you don't expect this sort of thing to happen," said Mrs. Harriman, who is still grieving over the loss of her favorite hunting horse. "It was a beautiful chestnut with a white face. I suspect it was the white face [in the moonlight] that did him in. The poor thing."

The killings, which police suspect are related to a spree of similar animal shootings in Loudoun County over the past year, have frightened many of the landed gentry into pulling their horses out of groomed pastures at night and putting them into barns. A Virginia state trooper is investigating the killings full time. Sen. John Warner (R-Va.), the wealthy owner of Atoka Farm on Middleburg's outskirts, has called Mrs. Harriman to offer his condolences on the death of Wingrove.

In hunt country, the home of an estimated 60 to 100 millionaires, fine horses are a beloved component of lives steeped in pastoral splendor. Laborers are sent into the pastures to pick thistle plants so prize horses and cattle can't eat them. Animals are meticulously groomed and given the best medical care.

The rich, with their horses waiting outside, gather regularly for hunt breakfasts and conversation before riding off to the hounds. r

The animal assassin has shocked local owners by introducing random violence and destruction into this culture of privilege and ease, breaking all the discreet rules about how people should behave.

"I'm desperate. Everbody is," said Sheila Riemenscneider, who, as master of the the Middleburg Hunt, leads 30 riders three times a week in search of a fox.

I think [the animal assassin] is a nut, a nut who wants publicity. It has got to be somebody just horrible. It is a terrible thing," said Mrs. Riemenschneider, who owns a 302-acre horse farm near Middleburg.

Trooper John S. Holsingr, who is investigating the killings, believes the offender is a crack shot who lives in the Loudoun County area and who is motivated in the senseless shootings by "pure meanness." Holsinger said he has several suspects in the shootings and that an arrest is possible this week.

The trooper believes that the same person responsible for the shootings three weeks ago near Middleburg also shot, a Holstein milk cow on Oct. 26 near Waterford in the northern part of the county. The cow was shot between the eyes with a high powered rifle. The bullet was extracted Wednesday from the cow's skull, and will be compared with bullets used in two later killings.

In the past year, at least three other cows and one horse -- a pony shot five times with a high-powered rifle -- have been killed in Loudoun. Holsinger says he thinks many other animals have been shot recently but believes their owners simply buried them without looking for bullet wounds.

A man claiming responsibility for the shootings called a local newspaper on Nov. 8, claiming that the killings will continue unless hunting in the area is stopped. Holsinger says the call probably was made to throw him off the track of the investigation.

While the investigation continues, alarmed horse owners have obtained promises from State Police and the Loudoun County Sheriff's department that patrols in the hunt country will be stepped up.

"I think that everybody around here is upset," said George A. Horkan Jr., an Upperville lawyer and horse owner. "My god, there are horses around here worth hundreds of thousands of dollars."

County officials estimate there are more than 6,000 horses, 25 percent of them thoroughbreds, in the area's rolling pastureland. Limestone in the soil, a source of calcium for growing horses, makes the grass sweet and has made the hunt country one of the world's finest horse breeding areas.

At Rokeby Farms, a 4,000-acre estate owned by Paul Mellon, one of the world's wealthiest men, there are racing thoroughbreds whose value is considered inestimable. At many other estates, it is not unusual to see thoroughbreds worth more than $100,000.

Peter Wilson, a trainer who has worked with horses in the area for 20 years, now advises horse owners to keep their animals away from paved roads at night.

"I've never known anyone to lose a horse around here the way Mrs. Harriman lost her hunter," said Wilson. "Can you imagine the death of a valuable horse that you dearly love?"

"Mrs. Harriman, who rode Wingrove four times a week until the horse was shot, said she remains "in shock" that someone would shoot her horse without any apparent reason.

At Willow Oaks, the 42-acre $444,000 estate purchased by her husband two years ago, Mrs. Harriman has ordered that a fence be built to keep her other horses from getting within easy rifle range of Rte. 626, where the animal assassin apparently fired the two shots Nov. 1.