A forest fire in a canyon on South Mountain in Western Maryland that raged out of control for three days was contained yesterday and firefighters hoped to extinquish it by today, according to the Washington County Fire Department.

Nearly 200 firefighters have worked continuously since Friday to battle flames that spread over about 58 unpopulated acres on federally owned property near the Appalachian Trail at Boonesboro.

Three firefighters have suffered minor injuries. One was taken to Washington County Hospital in Hagerstown with a sprained back and two were treated at the scene for burns, a spokesman said.

The cause of the fire is unknown, but officials blamed its severity on dry conditions and rough terrain that complicated firefighting efforts.

Winds and a brief storm whipped the fire across a fire line yesterday, according to David Pheil of the county fire department. "It's burned everything in its path," Pheil said.

"It's been extremely dry--we haven't had any measurable rain in two months--and it's extremely rocky . . . the fire pops out where the dead underbrush is," he said. Pheil said firefighters were "dropping like flies" Sunday when the temperature reached 100 degrees, although none of them required hospitalization.

Over the weekend, a Maryland State Police helicopter dropped more than 15,000 gallons of water on the fire. Yesterday alone, police said, it dropped 6,000 gallons. "Other than for practice, this is the first time [the helicopter has] been used," said Sgt. Gary Bockelmann. It's needed, he said, because the fire is "in a little canyon that is just so inaccessible by land."