KANSAS CITY, Mo. (AP) — Three men were found dead Monday morning at a Kansas City, Missouri, home after a report of carbon monoxide at the home.

The Kansas City Fire Department responded to the scene just before 7:30 a.m. and found three men believed to be in their 20s. Their names and exact ages have not been released. Fire officials say crews detected elevated levels of carbon monoxide inside the home, but the official cause of death remains under investigation.

Police have taken over the investigation.