More than two dozen people were sickened by carbon monoxide at a building housing a Bank of America branch in Flagstaff on Tuesday.
Two bank workers who met firefighters complained of being ill, and as they were being treated 8 to 10 more people approached and complained of similar symptoms. Those affected complained of headache, nausea and vomiting, all similar to carbon monoxide poisoning.
Firefighters called for extra help and set up a triage area as the building was evacuated and searched, Johnson said.
In all, 25 people were evaluated and five hospitalized with severe symptoms of carbon monoxide poisoning. An unknown number of people who had gone home sick also were affected. They either went to the hospital or sought medical attention on their own.
Firefighters measured carbon monoxide gas levels as high as 500 parts per million. At that level, "not more than 20 or 30 minutes and it's going to be your demise," Johnson said.
Normal readings in a home where a well-vented oven is operating is from zero to 20 parts per million.
A cause has not been determined, but Johnson said that such incidents are usually traced to a faulty heater, water heater or cooktop.