A 15-year-old Northwest Washington girl has been charged with arson in a fire last week that caused more than $2.5 million damage to a C&P Telephone Co. office building in Burtonsville where she worked as a member of the cleaning crew, Montgomery County fire officials said yesterday.

The girl was questioned by fire investigators and charged on Monday with starting the three-alarm blaze, which broke out about 9 p.m. Friday at 13101 Columbia Pike. Officials declined to discuss a possible motive for the fire.

The fire apparently began in a basement office of the four-story building and quickly spread, destroying computer equipment and telephone company records, according to Web Chamberlin, a telephone company spokesman.

Investigators said the basement level of the building was "completely wiped out" by the fire and that heavy smoke caused damage on the upper floors.

Thirteen firefighters and a security guard were injured in the fire and were treated for smoke inhalation at Holy Cross and Montgomery General hospitals and released.

Chamberlin said most of the equipment and records damaged in the fire were for corporate purposes and that customers in the area have not been affected.

"We haven't been allowed to go back in yet so we really don't know what all was lost," Chamberlin said.

Lt. Carvel Harding of the the fire marshal's office said the girl was an employe of Macke Building Services, which he said had a cleaning contract with C&P. Harding said the girl had been hired by the firm about a week before the fire and had been assigned to a night crew of 15 workers. Harding said she was alone in a basement office area when the blaze broke out.

The general manager of the cleaning firm could not be reached for comment.

Harding said the investigation was continuing.

Chamberlin said that about 500 employes who work in the building have been moved but are expected to return to their offices in the building by the end of the week.