A chronic shortage of guards at the District's juvenile center in Laurel was at least partly responsible for the escape of 17 youths, nine of whom were still missing yesterday, officials said.

The Oak Hill facility, where offenders of serious crimes are housed, had four guards on duty out of a normal deployment of eight when the youths cut a hole in the fence and fled Tuesday afternoon.

"We do consistently run shortages in the security perimeter area," said Youth Services Administrator Robert Little. "That's a product of resources available and personnel available."

One security post was unstaffed and roving patrols that monitor juveniles in the large recreation area were not operating, Little said.

This and the failure of an often troublesome motion detector -- which is supposed to sound an alarm if anyone approaches or breaches the fence -- contributed to the escape.

The city recently approved the hiring of 15 guards for Oak Hill. A spokeswoman for the personnel office said a list of applicants will be available by week's end.

The search for the escapees turned to the District. One of them, a 19-year-old, was committed to Oak Hill in connection with a drug-related killing and another, a 16-year-old, is awaiting trial on a similar charge. The eight already captured were found within five miles of the complex.

One of the juveniles still at large called the facility yesterday morning, apparently to chide officials.

"Some folks just can't miss a chance to brag," said Little.

The investigation into the escape, one of the largest in recent history, unveiled a plot hatched by five juveniles and an accomplice on the outside. The five crawled out of a hole they cut in the fence and were followed by 12 others who took advantage of the situation, said Little. In just minutes, the exodus matched the number of escapes since October 1989, which until Tuesday also amounted to 17.

In the past the juvenile center has been criticized for numerous failings including security problems. In 1986 the District entered into a consent decree as part of an out-of-court settlement of a class action suit to improve conditions.

Little, who was appointed in 1989, said Oak Hill has improved during the past year. He said the institution and its workers deserve credit for working with a difficult inmate population.

"We're dealing with the toughest of the tough young men in the District. These are youngsters who in any other jurisdiction in the country would be handled in an adult penal institution," he said.

The court-appointed monitor, Michael Lewis, said Oak Hill has shown some improvement, most significantly in the medical care available to juveniles. But the institution as a whole, he said, still needs major work, and changes are slow in coming.