The latest illness outbreak to hit Chipotle involved at least 647 people who got sick after eating at the chain's Powell, Ohio, location.
Health officials have now identified the problem: Stool samples from those sickened tested positive for Clostridium perfringens, a bacteria that forms when food is left at an unsafe temperature, CNBC reports; it's one of the most common causes of foodborne illness.
Local health officials inspected the store on July 26 and found violations related to food at improper temperatures, Business Insider reports; customers who got sick visited the store between July 26 and July 30. It was temporarily closed on July 30 after the illnesses were reported.
"Chipotle has a zero-tolerance policy for any violations of our stringent food safety standards and we are committed to doing all we can to ensure it does not happen again," Chipotle CEO Brian Niccol, who just took the helm in February, said in response to the findings. He said all employees across the nation will be retrained on food safety and wellness protocols, and that "recurring employee knowledge assessment" will also be added to the chain's daily food safety routines.
More From Newser: