Five of 13 youths who escaped Sunday night from the District of Columbia's Oak Hill juvenile detention center in Laurel remained at large yesterday, and a security guard at the facility was placed on administrative leave as officials investigated the incident.

Eight of the youths, including one police said was serving a term for murder, were captured within 12 hours after they escaped through an unlocked door at the facility, tunneled under one security fence and apparently climbed over another.

A security guard who officials said had been watching television with some of the youths prior to the escape has been placed on administrative leave pending an investigation of the incident, said a spokeswoman for the D.C. Human Services Administration, which operates the facility. She declined to name the guard.

"They were able to abscond because of a breach of security," said spokeswoman Joan Reeves.

The flight of the 13 juveniles, all aged 16 to 18 and placed at Oak Hill by the District's juvenile court, is believed to be the largest escape ever from the facility.

Maryland state police, U.S. Park Police and D.C. police all were alerted to the escape. According to the Park Police, five of the youths were captured near Rte. 197 and the Washington-Baltimore Parkway before dawn.

Around 6:30 a.m., a police spokesman said, three additional youths were apprehended after an off-duty officer spotted them flagging down a bus on the parkway near Greenbelt, about 12 miles from the facility.

Of the five still at large, police said, two had arrest records including armed robbery. One had been charged with assault with intent to murder and assaulting a corrections officer.

Oak Hill superintendent Rayford Myers said most of the escapees were serving terms for misdemeanors.

Oak Hill houses 150 youths in four cottages, each divided into two sections.

Myers said all of the escapees came from the same section of one of the cottages. They escaped around 8:30 p.m. when they slipped out of the cottage through an unlocked door after telling the guard they were going down the hall to the bathroom.

A second guard was on his lunch break at the time.