Health investigators warn against eating red, white, yellow and sweet onions from Thomson International Inc. because of a salmonella outbreak that's shown up in two-thirds of states.

If you can’t tell what company your onions came from, don’t eat them or sell foods made with them, and take extra care to disinfect surfaces and utensils that the vegetables touched, health officials advise.

The Salmonella Newport outbreak has sickened 396 people across 34 states. Among clusters of ill people who ate or shopped at the same places, many say they ate red onions, often raw in freshly prepared foods, including salads, sandwiches and salsas, the CDC says.

The FDA’s traceback investigation found that red onions from Thomson International of Bakersfield, Calif., are a likely source. Other types of onions from the supplier might be contaminated because of the way onions are grown and harvested, the CDC says.

The investigation continues to try to confirm the contamination source and figure out if other products are linked to the illnesses. The Public Health Agency of Canada is investigating a Salmonella Newport outbreak that may be related.

Thomson International recalled all red, white, yellow and sweet onions shipped anytime starting May 1 to wholesalers, restaurants and retailers nationwide. The onions come in mesh sacks in various weights from 2 lbs. to 50 lbs. and in cartons from 5 lbs. to 50 lbs. They are sold under the brand names Thomson Premium, TLC Thomson International, Tender Loving Care, El Competitor, Hartley’s Best, Onions 52, Majestic, Imperial Fresh, Kroger, Utah Onions and Food Lion.

The business says it issued the recall “out of an abundance of caution.”

“As of now no specific source of contamination or contaminated shipment has been identified, and FDA is also investigating other potential sources of contamination and has not yet reached a final conclusion,” the company’s recall notice says.

People with recall questions make call Kim Earnshaw with Thomson International at 661-845-1111.

To see more photos of recalled onion packages, go to the company’s announcement.

Update: Read about a recall and health alert for prepared fresh foods that used the onions.