Tyson Foods is recalling almost 12 million pounds of frozen chicken strips over concerns that the products may contain pieces of metal,

There have been at least six complaints of metal inside the chicken strips, with at least three people saying they had experienced oral injury, the U.S. Department of Agriculture’s Food Safety and Inspection Service said in a Saturday press release.

The recall is nationwide and includes multiple kinds of frozen, pre-cooked chicken strips produced between Oct. 1, 2018, and March 8, 2019, with “use by” dates of Oct. 1, 2019, through March 7, 2020. The products also include the number “P-7221″ on the back of the package.

The agency called the health risk from the products “high” and labeled it a “Class I” recall ― defined as “a health hazard situation where there is a reasonable probability that the use of the product will cause serious, adverse health consequences or death.”

The USDA also noted that this recall is an expansion of a previous recall from March when about 69,000 pounds of frozen chicken strip products were recalled for the same reason.