With more than a half-dozen commissaries on military bases in the continental U.S. reporting refrigeration outages this week, the Pentagon is acknowledging the problem but not making any guesses as to its source.

The outages affected at least Fort Irwin, California; Holloman Air Force Base, New Mexico; Naval Station Newport, Rhode Island; Little Rock Air Force Base, Arkansas; F.E. Warren Air Force Base, Wyoming; Robins Air Force Base, Georgia, and Fort Huachuca, Arizona, according to official announcements and social media reports.

Officials at the Defense Department would not say how many commissaries were affected in all or if the outages are being investigated as linked.

“The Department is aware of a possible refrigeration disruption at some Defense Commissary Agency commissaries,” a defense official said in a statement provided to Military Times. ”[The Defense Commissary Agency] has taken appropriate precautions to transfer products to alternate temperature-controlled locations to mitigate any product loss. Commissaries remain open, and all possible measures are being taken to ensure food safety. Beyond this we have nothing additional to provide.”

Defense commissaries are a benefit reserved for active-duty military members and their families as well as military retirees with base privileges. They offer at least a 25% discount from prices in comparable civilian grocery stores by selling food at cost, plus a small markup for staffing and facility maintenance.

Naval Station Newport publicly announced Wednesday on its social media pages that its commissary was among those affected.

“Due to refrigeration system issues at the commissary, the store will be open for the purchase of dry goods only until further notice,” the base said. “The deli, sushi bar, and grab and go sections will not be available to customers during this time.”

Fort Irwin posted its own update Thursday, saying the commissary would not sell eggs and milk “until the refrigeration systems are functioning properly.” It later revised its announcement, saying only dry goods would be available for purchase.

“Technicians are working diligently to troubleshoot and resolve the refrigeration issues currently affecting the Fort Irwin Commissary,” the base said on Friday. “At this time, there is no estimated time for completion.”

Fort Huachuca described its commissary incident as an “overnight equipment failure” on its Facebook page.

“ALL freezers went into defrost mode – ALL frozen food has spoiled,” it wrote.

F.E. Warren described a refrigeration “malfunction” in its public post.

While no official has offered an explanation for the cluster of outages, some have suggested that bad actors intentionally knocked linked refrigeration systems offline.

“It seems [continental U.S.] commissaries that have fridges linked to an online system have been getting shut off over the past few nights, and we’ve not seen any official notice put out to warn anyone so they can monitor their fridges more closely,” the popular military page “U.S Army W.T.F! Moments” posted. It added that reports indicated at least 18 commissaries were affected.

A defense official told Military Times it would be inappropriate to speculate as to the cause of the outages. It’s not yet clear how they’re being investigated.