Muslims Gather in Mecca for Annual Hajj Pilgrimage

Muslims from all over the world are flowing into the Saudi city of Mecca, just hours before the start of the annual Hajj pilgrimage.

At least 2.5 million Muslims are expected to join the annual ritual, which begins on Saturday.

Saudi Arabia has deployed some 100,000 security personal to ensure the safety of those making the pilgrimage. Helicopters, armored vehicles, ambulances and fire trucks are also part of the security operation.

Saudi Arabia has spent more than $1 billion rebuilding a two-level pedestrian bridge to avoid the deadly stampedes that have taken place during the Hajj in recent years.

The pilgrimage is one of Islam's five obligations. Every Muslim, if capable, must perform it at least once during his or her lifetime.