A stampede of religious pilgrims in a pedestrian tunnel in Mecca leaves more than 1,400 people dead on this day in 1990. This was the most deadly of a series of incidents over 20 years affecting Muslims making the trip to Mecca.

To the followers of Islam, traveling to Mecca in Saudi Arabia is known as performing the Hajj. The pilgrimage is one of the five pillars of the religion and must be done at least once in a follower’s lifetime, if personal circumstances permit. More than 2 million people make the journey every year. Typically, pilgrims celebrate the feast of Al-Adha and visit the area’s many holy sites during their stay.

The large number of people involved in the hajj has often led to tragedy. In 1987, a confrontation between Iranians and Saudis during an anti-American demonstration resulted in 400 deaths. In addition, a ritual in Mina has been the scene of several tragic incidents. There, in a valley near the birthplace of Mohammed, there is a giant pillar representing the devil. The pilgrims throw stones at the pillar over a three-day period. In 1994, 270 people died when too many rushed forward for the stoning. In 1998, at least 110 people were killed in a similar situation and another 180 were seriously injured. In both 2001 and 2002, more than 30 people died at Mina and, in 2003, another 244 pilgrims were killed in a stampede there. In 2006, 363 were killed.

Stampedes have not been the only source of tragedy–a fire in a tent in Mina killed 340 people and injured more than 1,400 more in 1997. Two separate plane crashes carrying pilgrims back home from Saudi Arabia in 1991 killed 261 and 91 people respectively.

In the 1990 tragedy, organizational failures by law enforcement officials combined with the enormous size of the crowd resulted in 1,426 people being crushed or suffocated to death in a long tunnel. Safety measures were taken in the aftermath, but with only limited success.