A 30-year-old prisoner escaped from the District's prison at Lorton Sunday in what embarrassed officials of the D.C. Corrections Department said was the first incident of its kind in two years.

Corrections officials identified the inmate as J.D. Wheeler, 30, who they said was discovered to be missing about noon from Youth Center 1, where he was being held while awaiting sentencing on an armed robbery conviction. He also faces a 10-year sentence in Maryland, D.C. officials said.

They said they did not know how Wheeler escaped from the youth center, which is surrounded by a fence and guard towers. No tracks were found in the snow near the fence, they said. They said they were investigating the possibility that he had walked out of the institution with visitors.

Corrections spokesman Edward D. Sargent called the incident "highly unusual" and "very embarrassing." He said the escape was the first in two years from one of the medium- or maximum-security facilities at the prison complex and said the case was "being given the utmost priority."

About 11:20 a.m. Sunday, according to John F. Henderson, acting administrator of Lorton's youth facilities, Wheeler entered the visiting hall on the second floor of the youth center administration building, where he received several visitors.

Inmates at the center meet visitors at tables in the visiting hall, under the supervision of at least one guard, Henderson said. Visitors to the youth center are not separated from prisoners by glass windows or other barriers, he said.

As a matter of routine, as the visiting period ended about noon, a woman guard searched the women's restroom. Henderson said she found trousers and a jacket of the type worn by inmates. An emergency count showed that Wheeler was missing, Henderson said.

An interior search was made, and the U.S. Marshals Service and the corrections warrant squad, which searches for escaped prisoners, were notified, he said.

Fairfax police spokesman Warren Carmichael said police were notified Sunday. "As far as we're concerned, they followed all the procedures."

The Lorton complex, in southern Fairfax County, has for years been a target of criticism from Fairfax leaders, particularly John F. Herrity, who was defeated for reelection in November as chairman of the county Board of Supervisors.

Audrey Moore, who has replaced Herrity as chairman, said yesterday that although residents are "very concerned about Lorton" and "don't like it being there," she had not heard about the incident and wanted more information before commenting.

In addition to requiring visitors to identify themselves at the prison gate and stamping their hands, Henderson said, security provisions require particularly close scrutiny of male visitors on arrival and departure.

The last reported escape from a Lorton medium-security facility occurred in September 1985, when a prisoner scaled three fences. The inmate was captured two months later. Other prisoners have since escaped from the minimum-security facility and from work details.