The Panera Bread restaurant on Highland Avenue in Seekonk, Massachusetts, is shut down after 18 people became ill there Friday morning.
According to WJAR-TV, 13 people were treated on the scene and five people were hospitalized after they became ill at the Panera Bread. Ambulances from five towns responded due to the number of patients.
Seekonk firefighters said they responded to the Panera around 11:15 a.m.for an initial 911 call from an employee reporting a strange odor in the building. The building was evacuated at this time.
The cause of the incident remains unknown, according to fire officials.
Authorities first thought that the air quality caused the sickness, but firefighters did not find anything unusual about the air quality. The fire chief is considering a possible Freon gas leak from an air conditioning unit.
Howley Bread Group, the local franchisee that operates the Seekonk Panera, issued a statement Friday afternoon saying that it appears the customers may have been exposed to carbon monoxide.
"Earlier today, several guests and associates at the Panera bakery-cafe in Seekonk exhibited symptoms consistent with possible carbon monoxide exposure," said Bahjat Shariff, operating partner of Howley Bread Group. "They were immediately taken to the hospital to be evaluated.
Shariff said the franchisee is working with the local health department to investigate.
"We have an unwavering commitment to the health and safety of our customers and employees," he said. "The cafe will remain closed until we are absolutely certain it is safe."