Authorities say a noose was found hanging from a lamp post outside a museum in the nation's capital, the third such incident in recent weeks.

U.S. Park Police Sgt. Anna Rose said the noose was found Saturday afternoon outside the National Gallery of Art.

She said her agency is currently investigating how it got there.

Tourists found a noose last month on the floor of the National Museum of African American History and Culture. A few days earlier another noose had been found on the grounds of the Hirshhorn Museum, which features contemporary art and culture.

The three museums are all located on the National Mall.