A prominent Northern Virginia lawyer who raised horses as an avocation was one of two passengers killed late Monday night when a single-engine plane crashed into a thick, wooded area near the Woodbridge Airport in Prince William County.

George F. Griffith, 47, of Middleburg, a horse breeder and contract attorney with a practice in Fairfax County, and Harrison E. Johnson, 45, of Adelphi, Md., the plane's pilot and a trainer on the Maryland racing circuit, were killed in the crash of the four-seat Bellanca, according to officials.

Lawrence E. Horning Jr., 30, of Severn, Md., also a horse trainer and the third passenger in the plane, was listed in serious condition yesterday in the intensive care unit of Fairfax Hospital, a hospital spokewoman said.

Griffith was one of the founding participants and the most senior justice -- or part-time judge -- in the Fairfax County Special Justice Program. The program was begun in 1975, when General District Court judges decided they no longer wanted to hear cases of involuntary commitment -- cases in which decisions are made about whether to commit people to state mental hospitals.

Griffith, a former president of the Alexandria Mental Health Association, told The Washington Post in a late 1983 interview that he believed "mental illness can be cured or put in remission by forced treatment."

The plane, enroute to Manassas, slammed into trees approximately 200 yards north of runway 01 at Woodbridge Airport at 10:06 p.m. Monday, according to a clock on board the aircraft, an investigator with the National Transportation Safety Board said yesterday.

It is not known whether the aircraft ever touched down on the 2,200-foot runway in a "touch-and-go" procedure, or whether the plane simply flew over the runway and into the trees, said NTSB investigator Gene Sundeen.

According to some young people who were camping a few hundred yards from the crash site, the plane's engine seemed to fail before it went down.

"We were awake talking and we heard an engine dying. Then we heard a big smash," said Jay Macredy, 14.

Sundeen refused to speculate on possible causes of the crash, which left wreckage strewn over an area about 150 feet long, and said his investigation will not be complete for several months.

The plane was owned by Jeffrey B. Rice, a long-time associate of Griffith's who shared office space with him for their separate law practices in Fairfax City, according to a spokesman for the Virginia state police.

The three men were returning from an excursion to the race track at Saratoga, N.Y., according to General District Court Judge James Fourqurean, a friend of Griffith.

Prince William County Fire and Rescue Department units were called to the scene about 10:40 p.m. by a resident who lives near the airport, a spokesman said.

Firefighters had to cut a path through the thick woods, which are part of the county's Lake Ridge Park, in order to move equipment capable of prying open the badly mangled body of the four-seat, blue and brown aircraft, according to a spokesman for the Virginia Civil Air Patrol.

Griffith owned several horses at his estate in Middleburg, according to those who knew him.

Johnson was recognized in Maryland horseracing circles as the first black trainer to achieve significant success in the state, said Jeff Weissman, a spokesman at Pimlico, where his horses often raced.

Johnson's best-remembered victory was at the 1973 Hopeful Stakes at Saratoga, when Grady O'Shay, a 2-year-old gelding he had trained, raced out of obscurity to beat several better-known and more expensive horses at the prestigious event.