Whole Foods and other U.S. grocers are only being partially stocked as a major food distributor continues to grapple with a recent cyber attack, a recent earnings call revealed.

North American wholesale distributor United Natural Foods confirmed this week that it was forced to take some of its systems offline after noticing unauthorized activity. At a financial quarter meeting Tuesday, June 10, CEO Sandy Douglas said the wholesale distributor is only supplying customers on a "limited basis" amid the crisis.

"We are partnering with customers across the country and across our formats in various short term mode to serve their needs as best as we possibly can," Douglas told investors. "Any way that we can help them meet their needs, we're doing."

The company is working with the FBI and other authorities to determine how to resume services and why the technology defenses failed, according to Douglas.

"We just got penetrated, so we will be continuing to look at every aspect of our defense, every aspect of how our tools are working, and what may be necessary to bolster it going forward, because it’s clearly an area that requires a tremendous amount of focus from companies today," he said.