The National Park Service used bark-colored and stone-toned paint yesterday to obliterate the work of vandals who spray-painted messages on 25 hardwood trees and a dozen boulders in Rock Creek Park, according to a Park Service official.

The damage, which was discovered over the Memorial Day weekend, was extensive, said Rock Creek Park Assistant Superintendent Cindy Cox. "They hit trees, logs and boulders and just kept going until they ran out of paint," Cox said. "We found an empty paint can at the end of the damaged area."

The neon orange and blue graffiti appeared along a half-mile-long path that connects 17th Street NW in the Mount Pleasant neighborhood with Beach Drive in the park, Cox said. The area, known as Piney Branch Park, is popular with dog walkers, she said.

Park Service employees took color samples into the heavily wooded area to match the paint as closely as possible to the browns and grays of nature, and then a three-man crew spent four hours on the cleanup work yesterday, she said.

The logs were chopped up and removed, she said.

Most of the vandalism was done in splashes of paint, but three names--Wendall, Kenny and Kevin--and messages to "kill white people" and an obscenity directed at white people were also found, according to Lt. Rob MacLean, a U.S. Park Police spokesman.

MacLean said the incident was under investigation. Anyone arrested in the incident could be charged with destruction of government property and participating in a hate crime. MacLean said police would increase patrols in the area as a result of the incident.

He said police had found gang names painted in the same area in recent years but did not know wether there was a connection between those incidents and the most recent one.

Cox said there have been recent graffiti problems in other areas of Rock Creek Park, including a picnic area near the William H.G. Fitzgerald Tennis Center and on the marquee for the Carter Barron Amphitheater, both located just off 16th Street and Colorado Avenue NW. She said spray-painted messages have been a continuing problem at Meridian Hill Park, also known as Malcolm X Park, near 16th and W streets NW.

At those locations, work crews use pressure washers to remove the paint, she said.

Cox said residents of Mount Pleasant were quick to notify the Park Service about the damage last weekend. She said the Park Service tries to remove the spray paint quickly as a way to discourage more vandalism.

CAPTION: Graffiti mars a sign in Rock Creek Park. Trees and boulders were vandalized.