A four-alarm fire that investigators called suspicious swept through six townhouses in the Burnt Mill condominium project in the White Oak section of Montgomery County yesterday leaving between 15 to 20 persons homeless, fire officials reported.

Eleven firemen suffered minor injuries fighting the blaze, which burned out the two-story townhouse units extending from 11132 to 11142 Oak Leaf Drive. Fire officials said they had not yet determined the cause of the fire or the exact location where it began.

"We are terming the fire suspicious because we cannot find an accidental cause," said Chief Warren Isman.

Isman said the fire probably began in the unit at 11138, which was the worst hit of the six brick and frame row houses.

Investigators said the fire was able to spread quick over the row of houses because each unit share a common attic. A building ordinance adopted in 1975 requires that fire walls be built between townhouse units, but the ordinance does not apply to the Burnt Mills units because they were built about a dozen years ago, according to a spokesman for Grady Management Inc., which manages the Burnt Mills project.

Each townhouse was worth $50,000, the spokesman said.

Sandra Lewis, who lived at 11140, said she was in her home recuperating from an illness when she heard a loud blast around 11 a.m.

"I thought somebody was trying to break in . . . then my husband opened the basement door to the utility room and saw smoke coming through from the house next door . . . He started screaming for me to get out of the house," Lewis said as she stood in the hallway of a friend's house, wearing slippers and a coat covering a nightgown.

One of Mrs. Lewis' pet poodles was rescued from a burning rooftop by a fireman. "It was just singed a bit," she said. Two German shepherds, belonging to a neighbor, Samuel Coe, were killed in the fire.

Eight-year-old Christopher Gilbert was home alone from school yesterday morning because he missed his school bus, which was delayed because of the snow. Christopher told his mother yesterday at a friend's house of racing out of the house when he first saw smoke. His 14-year-old sister dashed into the house shortly afterward and embraced her brother, crying. She said she heard about the fire over a radio while at school.

"We lost everything," said Claire Gilbert, mother of the two youngsters.

All the residents spent last night with either

The first alarm for the fire was sounded at 11:29 a.m., according to Lt. Leonard King, fire department spokesman. At 1 p.m., the fire was under control.

Yesterday's heavy winds, gusting up to 50 miles an hour, hindered firefighters and helped the fire spread, King said, while water used to fight the blaze produced an icy glaze on surrounding walkways. CAPTION:

Picture 1, Firemen fight blaze which swept through six townhouses in White Oaks, leaving 15 to 20 people homeless. Eleven firemen received minor injuries. Picture 2, Firemen Robert W. Evans rescued Sandra Lewis' poodle from burning house.; Picture 3, Sandra Lewis, burned out of townhouse, rests in neighbor's apartment. Photos by Charles Del Vecchio - The Washington Post