When you hear about a restaurant being shut down for a health hazard, you might assume that it’s because of an outbreak of illness, or because someone barfed. A Panera restaurant in Seekonk, MA closed down today to protect everyone after a carbon monoxide leak in the restaurant made 18 customers sick.

Restaurant investors are pretty nervous about the mere suggestion of foodborne illness: as soon as news reports surfaced that people in a Panera somewhere were sick, the company’s stock price fell. It recovered after investors learned that the food wasn’t implicated.

The symptoms of carbon monoxide poisoning include dizziness, headache, nausea, vomiting, dizziness, shortness of breath, confusion, blurred vision, and eventually loss of consciousness. 13 patients were treated on the scene, and five transported to the hospital.

More to the point, though, the local franchisee and the health department are investigating the cause of the leak, and the restaurant will remain closed until they find it. Only then will customers and employees be allowed back in.

Panera Shuts Restaurant After Possible Carbon Monoxide Exposure [Bloomberg]

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.