A handful of sick customers of four Mighty Taco locations ballooned into an outbreak of more than 100 people involving at least 11 locations of the fast food chain during the past week. The New York State Department of Health is working with health departments in Erie and Niagara counties on the investigation. The New York State Department of Agriculture and Markets is assisting. Refried beans from a third-party supplier are suspected as the culprit in the outbreak of foodborne illnesses, which had not yet been specifically defined Friday by public health officials. “At this time, the ECDOH (Erie County Department of Health) has received reports from 104 individuals reporting symptoms consisting primarily of nausea and vomiting after consuming refried beans from one of 11 Mighty Taco locations in Erie County between the dates of Sept. 27 and noon on Oct. 6. As this is an ongoing investigation, those numbers may change as additional reports are received,” according to a statement posted Friday by erie County officials. The chief operating officer of the regional fast food chain issued a statement Thursday, but the restaurants did not close. “For the past few days, Mighty Taco has been working both internally and with the Erie County Health Department to investigate illness concerns expressed by a small number of customers. Mighty Taco first became aware of the situation when five customers from only four store locations recently reported these concerns,” according to the statement from COO Russell Jasulevich. “The focus has now turned to the New York State Department of Health testing an isolated batch of refried beans provided by a third-party supplier for any possible cause. There are no conclusive results at this time but, in an abundance of caution, Mighty Taco has voluntarily removed that sole suspect batch of refried beans from our stores and that batch is no longer available to customers.” Erie County Health Commissioner Gale Burstein said patient interviews are ongoing, with the department’s full resources focused on the outbreak investigation. Health officials said the exact time when lab results will be available is unknown, but they are not expected before the end of next week at the earliest. Erie County residents who wish to report an illness that may be associated with this investigation may do so by calling the ECDOH Office of Epidemiology and Disease Control at 716.858.7697. There are 24 Mighty Taco restaurants in New York, including 18 in Erie County. (To sign up for a free subscription to Food Safety News, click here.)