The calls describe an emergency that grew quickly. In one, a caller reported an employee vomiting and feeling weak in a restroom. Another caller told dispatchers that 28 workers were affected and at least four were very ill.

Wilson County Emergency Management Agency officials said they initially received reports that 80 or more people might be sick. On arrival, crews assessed about 25 to 30 people with similar symptoms; 19 were transported to hospitals.

One caller suggested the illness might be linked to homemade rice brought into the facility. Health officials have not confirmed that account or identified a particular food as the source.

The Tennessee Department of Health is investigating a possible foodborne illness outbreak associated with a meal at the facility, with support from the Mid-Cumberland Regional Health Office and Wilson County Health Department. The agency had not identified the cause as of Oct. 14.

Maegan Eldridge of Wilson County EMA said the scale was unusual for the department. Potential food-related illness calls, she said, typically involve one or two people or a family, rather than dozens of workers.

Walmart said associate health and safety are a priority and that it is cooperating with local emergency management and health officials. The company also said its products were not the source and there is no risk to the public.

Dr. William Schaffner, an infectious disease professor at Vanderbilt University, said investigators will look for the cause and examine food preparation and handling. He urged people to heat food properly, cool it promptly and avoid leaving it out for extended periods, when contamination can allow illness-causing organisms to multiply.

Foodborne illness can cause vomiting and diarrhea, which may lead to dehydration. Schaffner said older adults, frail people and those with underlying conditions such as diabetes can face more serious effects.