“The cause of it was (that) one of the water heaters for the business had a mechanical failure and it was venting into the mechanical room itself which was then getting into the rooms of the residents”
More on this hotel CO incident in Lakeland, Florida. According to the video portion of this story, hotel was not required to have CO detection installed due to its age.
Carbon monoxide at Lakeland hotel sends 8, including children, to hospital (fox13news.com)