One of the most shocking and widely publicized events in recent world history began on September 1, 2004 when a group of militants seized School No. 1 in the town of Beslan, 30 km northwest of Vladikavkaz, the capital of the Russian republic of North Ossetia.
September 1 is known in Russia as the 'Day of Knowledge' and is when schoolchildren all over the country return to or begin their studies.
The militants killed 17 adults in the first hours of the siege, and then set up explosive devices around the school, concentrating them and the hostages in the gym. They then demanded that Russian troops pull out of the Chechen republic. The operation was organized by the late notorious Chechen warlord, Shamil Basayev.
The siege ended after three days when federal troops stormed the school - hundreds of people died as militants and troops exchanged fire. The authorities were widely criticized for their handling of the siege and for the events leading up to it. All of the terrorists bar one were killed.
During events in Beslan to remember the dead, flowers and floral wreaths were laid and candles lit in memory of the deceased. The proceedings started with the ringing of the school bell to mark the exact time when the school was seized.
Hundreds of people observed a minute of silence near the school gym where the hostages were kept during the siege. The school has not been repaired and has been left in ruins as a memorial to the dead.
The mourning ceremony will continue the next day, and a requiem concert will be given in Beslan on Tuesday night in memory of those who died in Russia's worst terrorist attack.
Russian opposition parties and human rights groups plan to hold three days of rallies in central Moscow and other cities across Russia.