The Islamic State terror group has murdered and then buried thousands of people in at least 72 mass graves, the Associated Press reports. At least 17 of the graves are located in Syria, and one of those includes the bodies of hundreds of members of a single tribe. When ISIS militants took over the area, they “exterminated” the entire community, the AP reports. Sixteen graves are in areas too dangerous to traverse in Iraq. The known numbers, which are incomplete, add up to more than 15,000 people killed and then stuffed into holes dug by bulldozers. For other graves, satellites can show some of the damage, including a massacre at the Badoush Prison in 2014, which left at least 600 men dead.