AP) MINA, Saudi Arabia - Vast crowds of pilgrims cast stones at walls representing the devil on the third day of the annual hajj on Friday as Muslims around the world began celebrating Eid al-Adha, the most important holiday of the Islamic calendar. The weather was sunny and hot Friday morning over the desert valley on Mina, a contrast to the unusually heavy rains that soaked the faithful on the pilgrimage's opening day Wednesday. The downpours caused heavy flooding in the nearby Red Sea coastal city of Jiddah, killing 83 people. The stoning rituals at Mina have long been the most hazardous of the hajj. The pilgrims -- more than 3 million this year -- file past three stone walls representing Satan and stop to pelt them with stones in a symbolic rejection of temptation. In the heavy traffic, crushes and pileups have killed hundreds, most recently in 2006. But since then, Saudi authorities have built a giant multi-story ramp around the walls, allowing people to stone on five different levels, spreading out the crowd and preventing jams. On Friday, the huge masses of men in white robes and women streamed over the sprawling structure, which resembles an immense, nearly kilometer-long (0.6 mile) parking garage. They furiously threw pebbles at the walls, denouncing the devil. Afterward, pilgrims shaved their heads in a sign of renewal -- or clipped off a lock if they balked at shaving themselves bald.