Tennessee health officials are investigating a possible foodborne illness outbreak at a Walmart fulfillment center in Lebanon after 19 people were taken to hospitals on Oct. 12. Wilson County Emergency Management crews initially responded to a report that a woman at the facility was experiencing symptoms of a possible food-related illness. Responders found several people sick and triaged about 25 to 30 patients, the agency said. The Tennessee Department of Health is working with the Mid-Cumberland Regional Health Office, the Wilson County Health Department and Walmart to investigate a possible outbreak associated with a meal at the facility. Officials have not identified a cause or said what food may have been involved. The site is a warehouse, not a Walmart store open to customers. Walmart said there is no risk to products at the fulfillment center or at nearby stores. A company spokesperson said the health and safety of employees is a priority and that Walmart is cooperating with emergency and health officials. Dr. William Schaffner, an infectious disease professor at Vanderbilt University, said an investigation can involve collecting samples from the environment and from people who became ill. Health officials may also assess symptoms, test specimens in a laboratory and work to prevent others from eating potentially contaminated food, he said. Schaffner said investigations into clusters of illness can help determine whether the incident points to broader contamination or disease spread. He advised keeping food either hot or cold rather than leaving it at room temperature for an extended period.