Twelve people were taken to area hospitals after what Anne Arundel County Fire officials believe was a carbon monoxide poisoning. County firefighters responded to the Navy Federal Credit Union at 1179 Annapolis Road sometime after 8 a.m. Tuesday for a report of workers experiencing symptoms associated with carbon monoxide poisoning. The construction crews said around 5 a.m. theu worked and used a propane -powered saw for about two to three hours in the building. Some of the workers started to feel ill and they called 911. Firefighters found elevated levels of carbon monoxide in the building. Three people were taken to Shock Trauma to be treated in their hyperbaric chamber, while nine others were taken to University of Maryland Medical Center to treat various symptoms.