Skulls and bones mark a mass grave found in a Siem Reap village.br br Authorities believe there are hundreds buried here and that they are among the millions murdered during the Khmer Rouge's bloody, five-year reign in the 1970s.br br Villagers came to the site to offer prayers for lost family members.br br (SOUNDBITE) (Khmer) 47-YEAR-OLD RESIDENT, CHEA NGEK SAYING:br br "I come to pray here because I do not know where my sister and her family were killed. They may be buried here so I am praying to them."br br The discovery was made on June 30 by a driver, who said the bones were buried five metres deep in the soil.br br The Khmer Rouge's "Year Zero" revolution wiped out a quarter of the country's population.