MECCA, Saudi Arabia — Muslim pilgrims stampeded on the last day of a symbolic stoning ritual at the hajj on Thursday, and the Interior Ministry said an unknown number of people were killed. The Al-Arabiya network reported that dozens of pilgrims died. The stampede occurred as tens of thousands of pilgrims filed past al-Jamarat, a series of three pillars representing the devil that the faithful pelt with stones to purge themselves of sin. The ritual has seen deadly stampedes in the past, including one in 1990 that killed 1,426 people and another in February 2004 that killed 244.