For two months, a task force of 14 Arlington police officers has been puzzling over a string of burglaries in South Arlington's Fort Scott neighborhood and in Crystal City. Burglars there have stolen cash and credit cards from 16 houses and seven hotel rooms.

Nearly every time, said Detective Rich Alt, the burglars entered through unlocked doors or windows. In the case of the house burglaries, the residents were almost always at home; but there were never any injuries, although a burglar once threatened a resident with a baseball bat.

"They would wake the residents up," said Alt. "Sometimes, the residents saw them as they were scampering out the door."

This week, acting on a tip from a Montgomery County detective investigating a case of credit card fraud, Arlington police made their first arrests in the case.

Ronald L. Henry, 18, of 203 Tennessee Ave., Alexandria, was charged with one count of unlawful entry. He was released on personal recognizance, and a hearing in Arlington General District Court is scheduled for Aug. 28.

A 16-year-old youth, also from Alexandria, was charged with five counts of burglary and is being held pending a hearing Aug. 16, Alt said.

"What was unusual about these, and the most alarming aspect for the victims, were that they happened in the dead of night when they were home as opposed to the daytime," Alt said.

He said the case is still under investigation.