The stampede occurred during the ritual known as "stoning the devil" in the tent city of Mina, about two miles from Mecca.

Hundreds have been killed in past years during the same ceremony.

"We have a stampede accident in Mina and civil defense is dealing with it," Interior Ministry spokesman Brig. Gen. Mansour al-Turki said.

The latest death toll, according to the civil defense ministry, is 310 but the numbers have been climbing steadily throughout the day.

Officials deployed 4,000 workers and 220 ambulances and other vehicles to Mina to help with the disaster.

In the ritual, crowds of pilgrims throw stones at three pillars, in a re-enactment of an event when Prophet Abraham stoned the devil and rejected his temptations, according to Muslim traditions.

The ceremony was the scene of stampedes and hundreds of deaths in the 1980s and 1990s as pilgrims passed a crowded bottleneck area leading to the small pillars on the ground.

In 2006, a stampede there killed at least 363 people.

After that, the Saudi government erected three massive pillars and completed a $1.2 billion, five-story bridge nearby where pilgrims can toss stones. It was meant to be a roomier atmosphere and more efficient way to accommodate the faithful.

The ritual

The stoning ritual is done over at least two days, where pilgrims stone three pillars at Mina -- believed to be where the Prophet Abraham stoned the devil when he tried to dissuade him from obeying God's orders to slaughter his son. According to tradition, the event was a test from God, who gave Abraham a ram to slaughter instead.

Thursday was the third day of the Hajj.

Ten days before the start of Hajj this year, a construction crane crashed through the roof of the Grand Mosque in Mecca, killing 107 people. At least 238 others suffered injuries when a powerful storm toppled the crane.

Losing one's life during the Hajj season is considered by many devout Muslims as an entry to heaven.

A spiritual climax

More than 2 million Muslims from around the world are attending the annual Hajj pilgrimage this year.

Known as the fifth pillar of Islam, the Hajj is an obligation upon every Muslim who has the financial means and the physical ability to perform it. For most, it is the spiritual climax of their lives, with many saving for decades to make the journey.

The pilgrimage, conducted over five days, includes detailed rituals such as wearing a special white garment that symbolizes human equality and unity before God; a circular procession around the Kaaba, Islam's holiest shrine; and the symbolic stoning.

It was also a tragic day for Muslims in Yemen on Thursday, where at least 29 people attending Eid prayers died when a bomb went off inside a crowded mosque in Sanaa.

(CNN)