A fast-moving forest fire that twice jumped trenches dug to hold it back has scorched 3,000 acres of the Minnewaska State Park Preserve near New Paltz, N.Y., an official said on Sunday.

Only minor injuries were reported in the fire, which started on Thursday in the northeast quadrant of the park, about 90 miles north of New York City in Ulster County.

But residents of a nearby hamlet have been told to prepare for evacuation, said Yancey Roy, a spokesman for the New York State Department of Environmental Conservation.

About 200 firefighters as well as local and state police officers, park rangers and others were involved in fighting the blaze, which was 80 percent contained by Sunday, officials said.

The cause of the fire was under investigation, Mr. Roy said.

The fire has been fueled by winds and dry, thick underbrush composed of mountain laurel, huckleberry and pitch pine, and its reach had doubled from 1,000 acres on Friday to 2,000 acres by Saturday.

Two fire lines initially held the blaze at bay, until flames raced up trees and released embers that were carried by the wind.

By Sunday afternoon, the fire had been contained near Kerhonkson Heights, the hamlet in the Town of Rochester at the edge of the park that was preparing for evacuation, Mr. Roy said.

Firefighters were trying to stop the fire's western front, which was advancing in a remote area accessible only by foot and all-terrain vehicles. Helicopters were dumping 500-gallon tanks of water drawn from a park lake onto the leaping flames.

Sunday's cooler weather, higher humidity and foggier conditions helped slow the blaze's advance, said Capt. Dan Walsh of the rangers.

All roads into the 20,000-acre park were closed, Mr. Roy said. He said it was the largest forest fire there in nearly 60 years.