KESQ reports that after an extensive investigation, health officials in Riverside County now say they have determined a possible source of the food-borne illness that sickened more than 100 shuttle drivers during the second weekend of the Coachella music festival.

“Tests conducted on food collected after dozens of employees of a shuttle bus company became ill last month detected a bacterial toxin that can cause the symptoms described by those who became sick,” Shane Reichardt of the Emergency Management Department confirmed to News Channel 3.

Officials say that toxin was found this week by the state health department laboratory and reported as Staphylococcal aureus (Staph) enterotoxin. The toxin “was detected in the food sample collected by a Los Angeles County resident who became ill shortly after eating a dinner catered for employees of a shuttle bus company on April 24.”

“Through collaboration with Environmental Health and the vendor, we have been able to interview hundreds of people who attended the dinner with the idea of determining the circumstances around the meal,” said Kim Saruwatari, director of the Riverside County Public Health Department. “The goal was to identify the specific food or item that caused so many to become ill.”

Investigators say the drivers who did get sick reported that they started feeling symptoms within hours of the meal.

However, “because sampled food items were mixed, health officials have not determined the specific food item that caused the sickness.”