Whole Foods employees say a major cyberattack on a leading distributor has left some store shelves and freezers empty.

In an internal memo obtained by the outlet, Whole Foods told staffers that the cyberattack on UNFI is its “ability to select and ship products from their warehouses.”

United Natural Foods Inc one of the largest U.S. grocery distributors whose clients include Whole Foods, took certain systems offline in recent days after the discovery of unauthorized activity on internal networks,

Customers on social media have expressed concern following the cyberattack, with some noting empty shelves at their local Whole Foods.

One of the largest food wholesale distributors in the US has suffered a data breach. Currently, the full impact is unclear.