D.C. police and fire investigators said yesterday they are searching for an arsonist who they believe set a recent series of fires at Anacostia High School in Southeast Washington that seriously damaged parts of the building.

Investigators said that a fire early last week caused about $200,000 damage to the school's kitchen and cafeteria, and that a spate of fires Monday morning damaged numerous classrooms.

Damage from the Monday fires was estimated at about $100,000, according to a fire department investigator.

Workers are repairing water, fire and smoke damage to the classrooms in preparation for the return of students after the Christmas holidays, a spokesman for the school system said. He said he believes the school will reopen as scheduled Jan. 2, though the kitchen and cafeteria may not be ready for use.

Arson investigators said they believe the fires were deliberately set by the same person, someone who is familiar with the layout of the school at 16th and R streets SE. They said they do not think the arsonist is a student.

The fire in the kitchen and cafeteria, which was discovered by school employes about 7 a.m. on Dec. 17, was apparently set the day before and burned itself out, investigators said.

School officials said that students were sent to Kramer Junior High School, two blocks away at 17th and Q streets SE, for lunch last week while repairs were being made.

On Monday morning, while students were on vacation, at least nine fires were set throughout the school, damaging numerous classrooms, investigators said. They said the fires were apparently started with trash.

While firefighters battled the blazes in one area of the school, other fires were reported in adjacent areas, and investigators believe the arsonist may have been inside the school setting the fires at the same time that firefighters were trying to extinguish them, a fire department spokesman said.

Investigators said another fire in the school's boiler room that occurred before Dec. 16 is believed to have been set by the same arsonist.