Former Pennsylvania Sen. Rick Santorum speaks at the Bella Donna Chapel in McKinney, Texas, on Wednesday. Rex C. Curry/Associated Press hide caption

itoggle caption Rex C. Curry/Associated Press

GOP presidential candidates in South Carolina Monday. Stephen Morton/Getty Images hide caption

itoggle caption Stephen Morton/Getty Images

Last March, nine people were killed in a gang shootout in the Pacific resort city of Acapulco, just as spring break was beginning for many U.S. schools. Bernardino Hernandez/AP hide caption

itoggle caption Bernardino Hernandez/AP