The U.S. Food and Drug Administration said Saturday that federal, state and local officials are investigating the outbreak linked to foods produced by Fresh & Ready Foods LLC of San Fernando, California. The FDA says the 10 people who fell ill were in California and Nevada, and required hospitalization.

The agency said the products were sold in Arizona, California, Nevada and Washington at locations including retailers and food service points of sale, including hospitals, hotels, convenience stores, airports and by airlines.

Federal officials said they started investigating the recent outbreak last year but didn’t have enough evidence to identify a source of the infections. They said the investigation was reopened in April when FDA investigators found listeria in samples collected from Fresh & Ready Foods that matched the strain from the outbreak.