MN – Pioneer Press – Authorities on Monday identified the man killed by a carbon monoxide leak that also sent three others to the hospital.

Killed was Robert Jon Corradi, 21, of Chisholm, the Chisholm Police Department said in a news release. The case remained under investigation.

Authorities received a 911 call from the home around 3:45 p.m. Sunday. When crews entered, they found high levels of carbon monoxide, Chisholm Volunteer Fire Department Chief Bob Brown has said.

“It really is a silent killer,” Brown said.

One 19-year-old man was taken to the Hennepin County Medical Center in Minneapolis, where police said he remained Monday. Two 20-year-old men were treated at a local hospital and released.

Authorities were looking at an appliance that wasn’t properly maintained as a potential source of the leak of the odorless, colorless gas, Brown said