Rescuers at the site of a stampede that killed and injured pilgrims in the holy city of Mina during the annual Hajj pilgrimage (Associated Press photo)

At least 700 pilgrims were killed in a stampede on Thursday outside the Muslim holy city of Mecca, where some two million people are performing the annual haj pilgrimage.Two Indians including a 60-year-old woman from Telangana were killed.Over 800 others were injured in the crush at Mina, a few km from Mecca, where pilgrims from across the world stay for several days during the last days of Haj.The stampede was caused by two large groups of pilgrims arriving together at a crossroads on their way to the stoning ritual at Jamarat, said Saudi civil defence officials. Pilgrims throw pebbles at a wall representing Satan in a symbolic "stoning of the devil" that marks the last day of the event.Over one lakh Indians were among the millions on Thursday marking Eid al-Adha, the feast of sacrifice. It has traditionally been the most dangerous day of haj because vast numbers of pilgrims attempt to perform rituals at the same time in a single location.Thursday's disaster was the worst during the Haj pilgrimage since 1990, when over 1,400 pilgrims were crushed to death in a tunnel near Mecca.In images on television and social media, wounded pilgrims were seen on stretchers next to rubble. More than 4,000 rescue workers and over 200 emergency vehicles are working to help the wounded."Work is underway to separate large groups of people and direct pilgrims to alternative routes," the Saudi Civil Defence tweeted.This is the second major tragedy at Mecca this month after over 100 people were killed on September 18 when a construction crane crashed on the Grand Mosque, Islam's holiest site.The pilgrimage, one of the largest religious gatherings in the world, has been prone to disasters in the past, mainly from stampedes, but their frequency was greatly reduced in recent years as the government spent billions of dollars upgrading and expanding haj infrastructure and crowd control technology.