Health officials warned Tuesday that certain turkey and chicken pot pies produced by ConAgra could be contaminated with salmonella; the food company has voluntarily stopped production at the Missouri plant that makes the pot pies.

The U.S. Agriculture Department said Tuesdays that consumers should avoid eating Banquet brand turkey and chicken pot pies and store-brand not-ready-to-eat pot pies with “P-9” printed on the side of the package.

These particular products may be linked to reported cases of salmonella, the USDA said. The department said ConAgra had voluntarily ceased production at its Missouri plant, where an investigation is ongoing.

The USDA’s Food Safety and Inspection Service sent investigators to the plant Monday. FSIS said consumers should not eat the products in question before the investigation is complete and the source of salmonella identified.

ConAgra has said in a news release that it believes the illnesses may be related to “consumer undercooking of the product.” The company advises consumers to cook the products thoroughly, as they are not ready-to-eat.

ConAgra emphasizes that the cooking instructions for these products are “specifically designed to eliminate the presence of common pathogens found in many uncooked products.”

The food company is offering refunds, through the mail or retailers.

ConAgra said it was working with USDA “to identify any additional steps that may be appropriate, including potential changes that may further clarify cooking instructions for consumers.”

The company also assures consumers that it is “revising its packaging to more clearly illustrate different cooking times for Banquet pot pies related to varying wattages of microwaves.”

The Centers for Disease Control and Prevention have recorded 139 cases of salmonella in 30 states, possibly connected to Banquet pot pies. A CDC representative said the largest numbers of salmonella cases had been reported in Wisconsin, Pennsylvania and Missouri.

There have been no fatalities so far linked to the pot pies.

Approximately 40,000 persons in the USA become infected with salmonella each year; the infection is known as salmonellosis and can be fatal. Around 600 people die annually from it. Among the symptoms are diarrhea, fever, dehydration, abdominal pain and vomiting.

This is not ConAgra’s first problem with salmonella. Earlier this year, the CDC investigated what it believed to be the first salmonella outbreak associated with peanut butter in U.S. history, specifically, ConAgra’s Peter Pan product and others.