Federal regulators are investigating a salmonella outbreak linked to packaged, diced onions that has sickened at least 73 people across 22 states.

Fifteen of the illnesses were so bad that people required hospitalization.

Gills Onions has already issued a recall for the products, which include diced yellow onions, diced onions and celery, diced mirepoix (onions, carrots and celery) and diced red onions. They have use-by dates of August 2023, the California-based company said.

Consumers and businesses should not eat, sell or serve these recalled products, the U.S. Food and Drug Administration said in a notice posted Monday on its website.

The onions were sold to foodservice and institutions nationwide and in Canada. They were also sold to retailers in Arizona, California, Idaho, Montana, Oregon and Washington. People in numerous additional states have reported cases.

The FDA and the U.S. Centers for Disease Control and Prevention are jointly investigating the outbreak, along with local partners.

Individuals and businesses should check their refrigerators and freezers for the products and throw them away, the FDA advised. People should not eat these onions.

Illness from salmonella usually happens within 12 to 72 hours of eating a contaminated food. Symptoms usually last for four to seven days.

Salmonella symptoms include diarrhea, fever and abdominal cramps. Children younger than 5, the elderly and people with weakened immune systems are more likely to have severe infections, the FDA warned.