The Food and Drug Administration today annonced that the agency is involved in the investigation related to the E. coli O157:H7 outbreak at Taco Bell restaurants. The FDA is actively working with state and local health officials, the U.S. Centers for Disease Control and Prevention, the firm, suppliers and distributors to determine the cause of the sicknesses and prevent additional infections.

The investigation has so far focused on green onions, or scallions, supplied to Taco Bell. According to the LA Times, New Jersey food safety regulators and the FDA are investigating two suppliers: McLane Foodservice and a Florence, N.J., facility operated by Irwindale-based Ready Pac Foods Inc.

Ready Pac today announced that it has ceased distribution of green onions until the investigation into the Taco Bell E. coli outbreak has been completed.