A sudden fire swept through a Gatihersburg apartment yesterday killing three young boys whose mother had gone to see a neighbor to make a quick phone call.

Firefighters found the bodies of 3-year-old twins, Joseph and Jason Savary, huddled near the window in the two-bedroom apartment in Suburban Park Village in upper Montgomery County. Their clothes had been burned off.

Their year-old brother Philip was found in a living room playpen. Officials said the children died of smoke inhalation.

Their mother, Theresa Savary, was restrained by neighbors and firefighters as she desperately tried to rescue her children while flames consumed the apartment.

"She was hysterical, screaming and crying for help," a neighbor, Chris Fletcher, said. "But we were all so helpless."

Fire officials said Mrs. Savary was washing clothes in a laundry room next door to the apartment, and went to use a neighbor's telephone in an adjoining building, before the fire started. Her husband john, who works for Montgomery Country Scrap Metal, was not home at the time.

Fletcher said the woman insisted that she left nothing on the stove during her absence and that there were no electric Christmas decorations in the apartment.

"We were all so frantic," Fletcher recalled. "My husband tried to get in there but he said there was so much smoke he couldn't make out the stairwell."

The cause of the blaze is not known. The fire broke out about noon near a couch in the living room of the ground floor of the housing development, a cluster of 12 three-story brick and cinder block buildings located off School Drive in rural flatlands west of Rockville.

Savary became hysterical as the body of her infant son was carried out and placed in a nearby ambulance. She was taken to Shady Grove Hospital for observations and released an hour later, a hosptial spokesman said.

The children's grandmother, Shirley Mullins, arrived soon after the fire was over and cried. "Where are they? Where are they?" She also was restrained from running into the gutted apartment.

Other family members and neighbors milled around quietly or cried in the cold wind after the disaster, stepping over the shards of smashed-out windows.

"Those kids hadn't even started their lives," sobbed Jesse Mullins, Mrs. Savary's brother, as he was supported by a friend.

"Somewhere, every year it seems, there is a tragedy around Christmas time," said John Lurahi, the resident manager of the apartments. "But why did it have to happen here?"

Fire officials said the smoke detectors in the apartment were ringing as they broke in with axes and hoses.

Neighbors could not understand why the twins did not flee the apartment.

"They could easily open the door themselves," Fletcher said.

"My God, how sad," mounred neighbor Kay Boles, slowly shaking her head. "Those twins were so playful. They would come out here on the lawn and frolic all the time."

One neighbor said Mrs. Savary went Christmas shopping for the children at K mart and Toys "R" Us last weekend. It was going to be the first Christmas for Philip, the blond baby they called P.J.

"Theresa was a very good mother," Fletcher said. "I know the children weren't playing with any matches. Theresa always kept them away from her kids."

"Those kids," one neighbor said, "were her life."