Lincoln Memorial temporarily closed after being vandalized with 'Free Gaza' graffiti

The Lincoln Memorial has been temporarily closed as cleanup crews have begun removing graffiti at the national monument that said "Free Gaza" in red paint, U.S. Park Police confirmed to ABC News.

Police are investigating the vandalism of the Lincoln Memorial in Washington, D.C., which was first discovered on Wednesday on the west side of the Reflecting Pool and Lincoln Memorial Circle. The memorial has since been temporarily closed to visitors.

The U.S. Park Service told ABC News Wednesday, "National Park Service conservators have begun the process of removing the paint this morning," adding that the cleanup may require multiple treatments over several days to remove.

The incident is not the first display of vandalism on a landmark in the nation's capital. In November, demonstrators spray-painted "Free Palestine" on several statutes in Lafayette Square, across Pennsylvania Avenue from the White House. That cleanup required specialized processes to remove the paint.

U.S. Park Police are still investigating the latest incident and are asking anyone with information to contact the United States Park Police tip line at (202) 379-4877, or email USPP_tipline@nps.gov.