At least six late-model automobiles have been accidentally destroyed by fire here in recent weeks as a result of what officials describe as an increasingly significant autumn fire hazard.

District fire investigator said that the six cars, and possibly others, erupted in flames after their catalytic converters ignited heaps of fallen leaves that accumulated beneath the vehicles.

The converters, installed as part of a car's exhaust system to reduce emission of pollutants, can reach temperatures as high as 1,600 degrees, and retain their heat long after the engine has been turned off, fire officials said.

They warned that autos equipped with these devices should never be parked near flammable materials of any kind.

D.C. fire investigators said the first such fire here this year occurred on a NorthWest residential street about two weeks ago. Three others occurred last week in the same neighborhood of Southeast near Fort Dupont Park where leaves have been piled knee-high along the curbs, they said.

"The residents over there had obviously worked hard to rake the leaves off their lawns," one investigator said, "But the city just hasn't gotten around to scooping them up yet." He said each of the three Southeast fires -- on Highwood Drive and Highwood Place SE -- broke out within an hour after the cars were parked.