Rochester, MN –
“RFD officials say after investigating, a carbon monoxide leak was confirmed, and hotel guests were evacuated…fire dept. worked with the Kahler’s maintenance staff to identify and stop the source of the carbon monoxide.”
No information released on the source nor if there is any installed CO detection onsite.

Carbon Monoxide leak reported at Kahler Grand Hotel in Rochester – ABC 6 News – kaaltv.com

The Rochester Fire Department and then worked with the maintenance staff at the hotel to identify the source of the carbon monoxide. That source was not identified in the Rochester Fire Department news release.

https://krocnews.com/600-rooms-checked-due-to-co-leak-at-kahler-grand-in-rochester/