LIMA, Peru — Archaeologists in northern Peru say they have found evidence of what could be the world’s largest single case of child sacrifice.

The pre-Columbian burial site, known as Las Llamas, contains the skeletons of 140 children who were between the ages of 5 and 14 when they were ritually sacrificed during a ceremony about 550 years ago, experts who led the excavation told The Associated Press on Friday.

The site, located near the modern day city of Trujillo, also contained the remains of 200 young llamas apparently sacrificed on the same day.

The burial site was apparently built by the ancient Chimu empire. It is thought the children were sacrificed as floods caused by the El Nino weather pattern ravaged the Peruvian coastline.

“They were possibly offering the gods the most important thing they had as a society, and the most important thing is children because they represent the future,” said Gabriel Prieto, an archaeology professor at Peru’s National University of Trujillo, who has led the excavation, along with John Verano of Tulane University.

“Llamas were also very important because these people had no other beasts of burden, they were a fundamental part of the economy,” Prieto said, adding that the children were buried facing the sea, while the llamas faced the Andes Mountains to the east.

Excavation work at the burial site started in 2011, but news of the findings was first published on Thursday by National Geographic, which helped finance the investigation.