About 100 firefighters from four counties in Southern Maryland, joined by state forestry agents and neighboring Amish families, yesterday battled a brush fire that consumed more than 50 acres near Mechanicsville, 40 miles south of Washington.

The blaze, as well as more than a dozen smaller brush fires in the Washington suburbs, came as authorities warned that recent dry weather poses a severe risk of fires in Maryland and Virginia. "It has gotten to the critical stage," said James Garner, Virginia's state forester.

The fire, off Cooney Neck Road in St. Mary's County, broke out in a swampy, wooded area. The terrain forced firefighters to leave their trucks and heavy equipment and walk to the scene with hand-operated, five-gallon water packs on their backs, fire officials said.

Jimmy Mattingly, vice president of the Mechanicsville Volunteer Fire Department, said firefighters used rakes and shovels to clear brush away from the perimeter of the fire in an effort to contain it. "We even had some private contractors with heavy equipment . . . trying to make some roads in there," Mattingly said.

The fire, which broke out early yesterday afternoon, was brought under control by about 6 p.m., Mattingly said, although firefighters remained at the scene until nearly 9. Mattingly said no injuries were reported and no one was evacuated from the region.

A total of 17 fire companies from St. Mary's, Calvert, Anne Arundel and Prince George's counties were summoned to the scene. It was the worst brush fire in that area in about 15 years, Mattingly said.

Montgomery County fire officials also reported what one described as a "pretty good-sized" brush fire that began near Olney Mills yesterday morning.

Firefighters took about two hours to extinguish the fire, officials said. They would not disclose details about the blaze.

Authorities in Maryland and Virginia said the threat of forest and brush fires has risen because of recent dry weather, high temperatures and strong winds. In the Washington suburbs, the officials said, a high "Class 3" fire hazard rating is in effect. There are five classes of fire ratings, with Class 5 the highest. Much of central and southwestern Virginia was designated as a Class 4 risk.

"We could have serious fires on days like today, especially with the high temperatures predicted for Easter," said Deborah L. Mills, a spokesman for the Virginia Division of Forestry.

Officials said weather was the main factor contributing to the high risk of fire. There has been little rain and low humidity for the past several weeks throughout the area, leaving trees, brush and so-called forest fuels -- the dried grasses and leaves on the forest floor -- very dry.

Similar weather in the summer would be less of a threat, officials said, because green leaves and grass are less flammable. The early spring's bare branches present a particular hazard, and officials said mid-February to early May is regarded as peak fire season.

Officials cautioned homeowners to delay burning dead leaves, grass and trash and to use caution if they prepare outdoor barbeques.

"Easter weekend seems to be a notorious weekend for fires," Mills said. "The days are warming up and a lot of people are outside in the woods, burning their gardens off and so forth."

In Virginia, it is illegal to burn objects within 300 feet of brush and woodland except between 4 p.m. and midnight.

Officials warned that a discarded cigarette could cause a fire.