MINA, Saudi Arabia -- Despite all the safety precautions, all it took was some dropped baggage in the midst of a jostling crowd of thousands of pilgrims to cause a deadly crush at Islam's annual hajj.
At least 345 people were killed and 289 injured Thursday when pilgrims tripped over their belongings and each other, pressed by hundreds behind them and smothering those screaming beneath them.
"I saw people jumping over each other," said Suad Abu Hamada, an Egyptian pilgrim who was nearby when the stampede broke out. "The bodies were piled up. I couldn't count them, there were too many."
The tragedy underlined the difficulty of managing the hajj pilgrimage, one of the biggest religious events in the world, which this year drew more than 2.5 million people.
It took place during a ritual that has been plagued by stampedes in the past: the stoning of three pillars called al-Jamarat. The pillars, located in the desert plain of Mina outside the holy city Mecca, represent the devil, and the faithful pelt them with stones to purge themselves of sin.
In 1990, a stampede at the site killed 1,426 people, and another in 2004 killed 244.
Since then, Saudi authorities widened ramps leading to the platform where the three pillars are located and created more emergency exits in an attempt to accommodate the crowds and avert stampedes.
The small, round pillars were replaced with 26-yard-long walls to allow more people to stone them at once without jostling each other. The walls extend down through the bridge and protrude underneath, so pilgrims below can also carry out the stoning without going above.
The 2005 pilgrimage that immediately followed the changes went without disaster, winning praise from participants.
But Thursday's stampede occurred below the platform, near one of the entrance ramps.
Thousands of pilgrims were rushing to complete the last of the three days of the stoning ritual before sunset, when some began to trip over dropped baggage, causing a large pileup, Interior Ministry spokesman Maj. Gen. Mansour al-Turki said.
Many pilgrims carry their personal belongings -- such as tents, clothes or bags of food -- with them as they move between the various stages of the hajj.
"Suddenly, I heard crying, shouting, wailing. I looked around and people were piling upon each other," said Abdullah Pulig, an Indian street cleaner.
Afterward, bodies were lined up on the pavement nearby, covered with white sheets, and emergency workers rushed the injured away on stretchers. Police cleared part of the site, but thousands of pilgrims continued the stoning ritual nearby.
Mina General Hospital, a small facility near the al-Jamarat site, was filled with injured, and some victims had to be sent to hospitals in Mecca and Riyadh, Dr. Ismail Abdul-Zaher said.
Many pilgrims expressed frustration over the repeated disasters at al-Jamarat.
"This should not happen every year. It should be stopped, it's a scandal. There must be a way to organize this better," said Anwar Sadiqi, a pilgrim from Pakistan.
Ensuring a smooth pilgrimage is a key concern for Saudi Arabia's royal family, which bolsters its legitimacy by touting its role as the "custodian of the holy cities" of Mecca and Medina, where Islam's 7th-century prophet Muhammad was born and lived.
Crown Prince Sultan Bin Abdel Aziz told reporters the kingdom had "spared no effort" to avoid such disasters but, he added, "it cannot stop what God has preordained. It is impossible."
"We feel pain and sorrow for them and for their families and we send our condolences," the prince said on Al-Ekhbariya television.
The hajj is a complex balance of safety with Islam's requirements that every able-bodied Muslim should perform the pilgrimage at least once. Saudi Arabia sets a quota of participants, allowing every nation to send 1,000 pilgrims for every 1 million in population.
The three-day stoning ritual in particular is a nightmarish problem in crowd dynamics.
Hundreds of thousands of pilgrims must move up the ramps onto the platform, maneuver from pillar to pillar and hit each with seven stones, then exit.
Many of the pilgrims are in a rush because of the time constraints on the ritual and their anxiety about past stampedes.
Traditionally, stoning was carried out from midday to sunset.
Shiite Muslim clerics have issued edicts allowing pilgrims to do the stoning in the morning, and some Sunni clerics have followed suit in an attempt to space out the crowds. But some clerics following Saudi Arabia's strict Wahhabi interpretation of Islam urge the faithful to stick to the midday start.
About 60,000 Saudi police and soldiers patrolled the Mina plain once the stoning ritual began Tuesday to direct pilgrims. Helicopters flew overhead, and authorities monitored the pilgrims from a control room through closed-circuit TV.
But some people complained that police did little to help.
"They look indifferent. They don't carry out their duties seriously," Iftikhar Hussein, an Iraqi pilgrim, said. "This looks like a garage rather than a holy site."
"If hajj is a duty for every able-bodied Muslim, it should be a duty for the government" to ensure it is safe, she added.
Signs giving directions are few, and pilgrims often ignore regulations. Peddlers selling food and souvenirs also impede the pilgrims.
Saudi Arabia has announced plans for further changes to the site in coming years that it says will allow 500,000 pilgrims an hour to carry out the stoning.
Among the changes, the platform is to be expanded to four levels, with 12 entrances and 12 exits. Also, there are plans to bus pilgrims to al-Jamarat from a nearby tent city in the desert rather than allow them to make their own way to the site.
Thursday evening, the highway from Mina to Mecca was packed with buses, trucks and cars carrying pilgrims to the holy city for Friday's final rite of the hajj: the "farewell tawwaf" -- a walk around the Kaaba, the black stone cube that all Muslims face when they perform daily prayers.