Seven soldiers from the Army's prestigious Old Guard honor unit, which performs ceremonial duties at such venues as the White House and Arlington National Cemetery, are being investigated in connection with several burglaries at homes and businesses in Montgomery, Arlington and Fairfax counties, authorities said yesterday.

Montgomery County police have obtained arrest warrants for three of the soldiers, all enlisted men, charging them with first-degree burglary, auto theft and other crimes, a police spokesman said. Officials declined to identify the soldiers last night, and Montgomery police had made no arrest because authorities had not decided whether the cases will be handled in civilian or military court.

The charges stem from a Thanksgiving weekend break-in at a home in the 9500 block of River Road in Potomac. While the owners were away for the holiday, thieves entered the house through a ventilation shaft in the roof and stole several cameras, two laptop computers, a desktop computer and a watch as well as a 2000 Porsche Boxter and a 2001 Mercedes-Benz, police said.

The three suspects were arrested in the stolen Porsche in the District on Jan. 6, according to Montgomery police. D.C. police last night would not release any information about the case. Montgomery police said two of the soldiers are 19 years old, and one is 18. They were released after their arrests in the District and are being monitored by military authorities, officials said.

An investigation tied them to the burglary in Potomac, authorities said.

"We only have three in the stolen car," said the Montgomery police spokesman, Officer Derek Baliles. "We don't know how many were in the house."

A member of the family living at the house said last night that police told them that night vision goggles were used in the burglary.

Authorities said the probe expanded to include seven Old Guard soldiers and other burglaries in Fairfax and Arlington counties.

"These counties have had break-ins that may or may not be related," said Marc Raimondi, a spokesman for the Army's Criminal Investigation Command at Fort Belvoir. "Everybody's talking to everybody."

The allegations have shocked Army officials at the Military District of Washington, which oversees the Old Guard, based at Fort Myer in Arlington. The honor unit, known formally as the 3d U.S. Infantry, is the oldest active-duty infantry unit in the Army, dating to 1784.

The unit, which also provides security for the District in times of emergency, responded to the Pentagon after the Sept. 11, 2001, terrorist attack, with its soldiers helping to remove many of the dead from the rubble.

The Old Guard prides itself on accepting only top people, adding to the Army's embarrassment and surprise over the investigation.

"We are committed to ensuring that our soldiers abide by the law and behave as good neighbors," said Maj. Gen. James T. Jackson, commander of the Army's Military District of Washington. "When they do not, we will ensure all allegations are thoroughly investigated and dealt with in an appropriate manner."

Staff Writer Martin Weil contributed to this report.