PRINCE GEORGE'S COUNTYFurnace Sets Off Apartment Building Fire A faulty furnace sparked a three-alarm fire yesterday that ripped through a District Heights area apartment building and displaced more than 50 people, Prince George's County fire officials said. Firefighters found heavy fire throughout the three-story building in the 1900 block of Brooks Drive about 5:30 p.m., said Major Chauncey Bowers, a fire department spokesman. No injuries were reported.

Firefighters took about 30 minutes to control the blaze, which investigators said was caused by a furnace in a first-floor apartment.

Officials estimated the fire caused $250,000 in damage. County emergency officials and the Red Cross last night were assisting 27 adults and 26 children who could not return home, Bowers said.

-- Clarence Williams POTOMAC RIVERAn Estimated 40,000 Fish Killed in CharlesAbout 40,000 fish have been found dead along the Potomac River in southern Charles County in recent days, Maryland officials estimated yesterday. Robert Ballinger, a spokesman for the Maryland Department of the Environment, said the fish kill near Swan Point affected mainly white perch. He said that officials think it was not from pollution, but that the cause has not been found.

-- David A. FahrentholdFREDERICKBody of Suspected Mall Arsonist IdentifiedFrederick police yesterday recovered a gun they say was used by a man who shot at officers and set a shopping center on fire this week. They also announced that a body found Tuesday in the rubble of the shopping center has been positively identified as that of suspect James C. Douglas, 30, of Frederick, who they say died of smoke inhalation. Police said a .25-caliber Colt Pocket Pistol used by Douglas on Monday was recovered from the rear of the store. "The weapon was cocked with a live round in the chamber and one additional round in the magazine," police said in a statement.

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MONTGOMERY COUNTYPolice ID Boy Critically Injured in CollisionMontgomery County police yesterday identified a 12-year-old boy critically injured in a collision between a tow truck and a minivan as Carson Daniel Fehner of the 12000 block of Summit Ridge Terrace, in Germantown.

Police said the accident occurred about 8:15 p.m. Tuesday when the minivan driven by the boy's mother, Terry Fehner, 51, turned left in front of an eastbound tow truck on Germantown Road near Dawson Farm Road.

Neither Fehner nor the tow truck driver, Earl Jobe, 48, of the 3100 block of West Springs Drive in Ellicott City, was injured.

Carson remained hospitalized yesterday.