On August 23, 2011, the Washington Monument sustained damage during the 5.8 magnitude 2011 Virginia earthquake; over 150 cracks were found in the monument. A National Park Service spokesperson reported that inspectors discovered a crack near the top of the structure, and announced that the monument would be closed indefinitely. A block in the pyramidion also was partially dislodged, and pieces of stone, stone chips, mortar, and paint chips came free of the monument and "littered" the interior stairs and observation deck. The Park Service said it was bringing in two structural engineering firms (Wiss, Janney, Elstner Associates, Inc. and Tipping Mar Associates) with extensive experience in historic buildings and earthquake-damaged structures to assess the monument.