A deadly outbreak of avian flu has wiped out nearly half of the egg-laying hens in the U.S., leaving grocery store aisles empty, driving up prices and forcing retailers to limit purchases to curb hoarding.

Videos going viral on social media have shown frenzied scenes in the egg aisles of major retailers like Trader Joe’s and Costco.

Due to the bird flu outbreak and rising demand, Costco is limiting egg purchases to three cartons per customer.