Diamondback’s Casino was closed by the Kittitas County Health Department Tuesday afternoon while it investigates a possible food-borne illness outbreak.

The Health Department reported more than 20 people have called with complaints of diarrhea, nausea and vomiting after eating at Diamondback’s sometime over the New Year’s weekend.

Diamondback’s manager and chef Bob Mayer said some people who attended the restaurant’s New Year’s Eve gathering, and some who ate at the restaurant on Saturday and Sunday reported having symptoms. He said several people who also ate at the restaurant on those days did not exhibit any symptoms.

The casino portion of the restaurant remains open though with a limited menu. Any foods served must be prepared by an outside source.