A South Carolina mental health patient died when staffers jumped on him in an attempt to restrain him, according to a report.

A probe into the death of 35-year-old William Avant determined he was suffocated at G. Werber Bryan Psychiatric Hospital in Columbia, The State reported on Monday.

Staffers said the incident occurred in January 2018 when they attempted to calm down Avant, who suffered from a chromosomal disorder known as Klinefelter syndrome.

Employees pinned the agitated patient down as he was face down on a hallway floor and lay on top of him for four minutes, according to the news outlet.

Officials said the staffers failed to check his breathing, as mandated in employee training for restraining patients.

When turned over, Avant had no pulse and was blue in the face, officials said. He was brought to a hospital, where he was pronounced dead.

“That’s inexcusable. I don’t understand that at all,” Anna Maria Darwin, an attorney for Protection and Advocacy for People with Disabilities, told the news outlet. “If you knew better, and you should have known better — either it’s very poor judgment or you knowingly disregarded your training — you’re not appropriate to provide direct care to people, especially vulnerable adults.”

The South Carolina State Law Enforcement Division has declined to press charges in the incident, The State reported.