A series of fires allegedly set in the basement storage rooms of five adjoining Adelphi garden apartment buildings left 50 families homeless early New Year's morning, according to Prince George's County fire officials.

The fire alarms that sounded between 2:37 a.m. and 3:04 a.m. brought more than 15 fire trucks and engines from both Prince George's and Montgomery counties to the scene as families fleeing the smoke and flames emerged into a pre-dawn rain.

There were only minor injuries reported, but some units were so badly gutted that 15 families were permanently displaced by the fire, according to Lawrence G. Brown, of the prince George's County office of emergency preparedness.

The fires caused an estimated $150,000 in damages, officials said.

Many of the displaced families, moved temporarily yesterday to the Adelphi Elementary School, where 20 Red Cross volunteers set up costs in empty classrooms and served food and coffee in the gym. The smell of smoke clung to the people's clothes.

"I'm just glad to be alive," said Ronald ald Lanthrip, 48, a mailman who bruised his arm opening a jammed door from his apartment at 9311 19th Ave. "If it were not for the smoke detector, Ihd be dead."

Nellie and Roger Jannifer were saying godbye to the last of their New Year's company around 2:30 a.m. when she smelled smoke. Roger Jannifer, a tow-truck driver, traced the fire to the basement trash room, evacuated his own family and thn began pounding on other doors in his building at 9410 Adelphi Rd., and in the building next door at 9412.

"There is nothing I can do about it but take it like it comes," he said. His wife Nellie, who had stood in the rain until 6 a.m. and was now wrapped in a blanket, said she was "disgusted."

"We can't go back," she said. "Our building is condemned."

Four of the 40 garden apartment buildings in the 390-unit Oakon Apartments complex were posted "unsafe" yesterday. But police said that once utilities were prepaired, tenants would be able to recoccupy units in all but one building.

Inside that three-story brick building at 9410 Adelphi Rd., Doris Roberts was allowed to rummage briefly through her basement apartment to retieve what clothes she could. Her bedroom digital clock-radio had stopped at 3:07 a.m. and water and mud had collected in the living room, but otherwise the $290-a-month, two-bedroom unit appeared relatively unscathed.

Roberts, a nurse, had moved into the apartment with her 3-year-old daughter two weeks ago.

Upstairs, apartment No. 103 was a balck charred ruin with broken windows. Other apartments in the building presented a similar picture.

"We're proceeding under the assumption the fires were deliberately set," said Capt. Duncan Monroe, of the Prince George's County Fire Department.

The most pressing concern of all tenants yesterday was finding a plance to live, both for the short term and for the long-range future. Some, like Doris Roberts, moved in with relatives. Patrick Hanley, a clinical coronary specialist with the Army, prepared to move his family, temporarilhy, to the Walter Reed Army Medical Center guest house.

Others waited for their landlord, the Dreyfuss Brothers firm, to find comparable lodging for them. By midday, Oakton resident manager Sharon Anderson had found units for six of the 15 percently displaced families. "I'm doing the best I can," she said yesterday.

The lucky ones, whose apartments were lacking only utilities and new window panes, merely waited. One of them, Christina Davis, 35, had just moved in from Takoma Park. "I haven't had a chance to hand my curtains, finish unpacking," she said.

Another was Ann Radin, a Silver Spring elementary school teacher whose apartment was virtually untouched by the blaze. With her 5-year-old son Sean draped around her neck, she had "closed my eyes and jumped" from her first-floor window ledge several feet above the ground. The two landed on top of three men who had urged them to leap. "Everyone was okay," she said.

It was then she realized, she said, that Leslie, the family cat, was still inside. A Red Cross volunteer went back to rescue the animal, which had passed out. The animal recovered after oxygen was administered to it.