DES MOINES, Iowa (AP) — A massive frozen foods recall involves millions of packages of fruits and vegetables that were shipped to all 50 U.S. states, Canada and Mexico.

Authorities worry it’ll be difficult to get consumers to dig through their freezers and check for products they may have bought as far back as 2014 from places like Costco, Target, Trader Joe’s and Safeway.

The more than 400 products from CRF Frozen Foods in Pasco, Washington, could be contaminated with listeria. Products tied to the plant have caused eight listeria-linked illnesses, including two deaths.

The CRF plant closed two weeks ago and CRF spokesman Gene Grabowski said the company is still trying to pinpoint the source of the contamination.

The U.S. Food and Drug Administration offers more information online (click here).