Officials in Arizona say lettuce supplied by Midwest Beef was the probable cause of an E. coli outbreak this summer that was linked to a Federico’s Mexican Restaurant in a Phoenix suburb.

Almost 100 people, including several members of a high school sports team and their families, were confirmed with E. coli in late July and early August, but no deaths were linked to the outbreak, according to a report from the Maricopa County Public Health Department. About 20% of the victims required hospitalization.

“Lettuce was by far the most suspect food item, and it is highly likely that it was the contaminated vehicle in this outbreak,” according to the Nov. 25 report. The report names Midwest Beef, Phoenix, as the supplier of meat and fresh produce to the specific Federico’s restaurant in Litchfield, Ariz., and other Federico’s locations and foodservice operations in the area.

Midwest Beef officials did not immediately return calls seeking comment on where the company sources the lettuce it sells.

The health department report said it was possible that the restaurant received a single batch of lettuce that could have been contaminated at any point in the continuum from field to fork.

“Lettuce handling protocols were observed in detail, and it was noted that if contamination had been present on a small amount of lettuce, it could have easily spread to contaminate other lettuce in areas such as the prep sink and shredder, or during storage in a large container,” the report states.

The restaurant voluntarily closed for two days while a third-party company cleaned and sanitized the location. Upon reopening staff implemented new protocols suggested by the Maricopa County Public Health Department.