Article Photos: Oklahoma City mayor says 12,000 to 13,000 homes damaged or destroyed by May 20 tornado 151/564

Franklin Graham, second from left, leads a prayer after workers installed crosses on Friday, May 24, 2013, outside of Plaza Towers Elementary for the seven victims killed at the school during the May 20 tornado in Moore, Okla. Photo by Aliki Dyer, The Oklahoman