HOLLAND -- West Michigan health officials say a restaurant in Holland has closed until further notice while authorities investigate an outbreak of illness that has affected at least 35 people who ate there. The Ottawa County Health Department says Margarita's Mexican Restaurant voluntary shut down during the probe. Health department spokeswoman Shannon Felgner tells Mlive.com that the illnesses were reported over the past several days. The department started its investigation Thursday after getting reports of 10 illnesses, mostly involving nausea, vomiting and diarrhea. So far, the cause of the outbreak hasn't been determined. Felgner says some samples from patients are being analyzed at Holland Hospital, and others may go to a state lab.