Hector Severight described his time at the Gordon Indian Residential School as a nightmare that still haunts him.

While there, Severight had to fight off physical and sexual abuse. Eventually, he ran away.

“It’s a totally different type of life,” he said.

While he made it out, new research released Monday showed that roughly 3,000 students died at residential schools across Canada. The identities of 500 of them are still unknown. The majority of the deaths were due to disease, but some were from running away, fires, and some were also due to suicide.

The new information came from the first systematic search of government and school records ever conducted for the residential schools.

Kerry O’Shea is a Saskatoon lawyer specializing in residential school claims. She said her clients paint a picture of cramped dorms where disease easily flourished. Some of her clients recall watching their friends and classmates get sick and die.

“They would see they were sick, then they would just disappear,” O’Shea said. “Part of the trauma was not knowing what happened to that other little student or brother or sister.”

According to O’Shea, in some cases, parents weren’t told of their children’s deaths until months later.

The research is part of an on-going investigation by the truth and reconciliation commission.