Muslim men gather at the shrine to Imam Hussein, the grandson of Islam's Prophet Muhammad, in Cairo, on April 4. The shrine is a leading pilgrimage site for Sufis, whose shrines have come under attack from members of the extremist Salafi movement in Egypt. (Associated Press)

Muslim men gather at the shrine to Imam Hussein, the grandson of Islam's Prophet Muhammad, in Cairo, on April 4. The shrine is a leading pilgrimage site for Sufis, whose shrines have come under attack from members of the extremist Salafi movement in Egypt. (Associated Press)