WinCo Foods on Saturday expanded its hamburger recall to include ground beef sold at its stores Washington, Oregon, Idaho, California, Nevada and Utah.

The original recall, announced a week ago, was for ground beef purchased at its Modesto, Calif., store from April 3-9. An independent lab involved with a survey of supermarket ground beef found that two samples purchased from the Modesto store were tainted with an E. coli O157:H7 bacteria that causes foodborne illness.

But, as government agencies investigated, “new information has come to light that potentially implicates WinCo’s ground beef suppliers,” the discount retailer said Saturday.

The recall time frame is expanded to include fresh hamburger packed in Styrofoam trays with a sale date of March 28 through April 9.