(CNN)Scientists have unearthed a dark secret in Peru.
The skeletal remains of more than 140 children and 200 baby llamas were found on the country's northern coast. It may be evidence of the largest child sacrifice in history, according to an exclusive report by National Geographic, released Thursday on its website. The remains of a man and two women were also found.
The sacrifices are believed to have taken place 550 years ago in the pre-Columbian Chimú Empire, in a sacrificial site formerly known as Huanchaquito-Las Llamas, close to a UNESCO World Heritage site of Chan Chan, in the modern town of Trujillo.
The children ranged in age from 5 to 14, according to the report. The baby llamas were less than 18 months old.
"Skeletal remains of both children and animals show evidence of cuts to the sternum as well as rib dislocations," the report says.
The children had their faces smeared with a red cinnabar-based pigment, the report says, which took place during the ceremony before their chests were cut open, most likely to remove their hearts.
"The sacrificial llamas appear to have met the same fate," the report states.
According to National Geographic, the children were "buried facing west, out to the sea." The baby llamas were buried facing east, toward the high peaks of the Andes.
Based on evidence from layers of dried mud, the report states it's believed that all the human and animal sacrifices took place at the same time. The three adults found had blunt-force trauma to the head and no grave, leading scientist to believe they, too, were part of the sacrifice.
The site where the children and baby llamas were found has been under excavation since 2011, when the site first made headlines after the discovery of 42 children and 76 llamas during an emergency dig.