According to media reports, the Fort Bragg Army Base in North Carolina first mentioned the blackout on Wednesday night and said no one knew when the power would be restored. A statement said the base is still open.
The outage also affected restaurants and commissioners at the base, which is home to about 52,000 soldiers.
The Womack Army medical center on the base indicates that its capacity is reduced and that some appointments in all the clinics on the base will have to be reprogrammed.
Visitors must call 911 to report suspicious activity.
