A power failure hit an AT&T facility in Bloomfield, Michigan on Sunday morning local time, which caused mobile service disruption in parts of the midwest region of the U.S., the company said on Sunday.

Though most services were back up on Sunday, AT&T said some customers may have experienced "sporadic service issues" on Monday as it "rebooted equipment impacted by power outages," the company wrote on its . However, as of a few hours ago, AT&T said it had fully restored services.

Frustrated AT&T subscribers on Sunday reported cell phone and data services being affected in multiple states and major cities such as Chicago from the outage. Some users also reported not being able to access AT&T's data network using Apple's iPhone or Research In Motion's BlackBerry mobile devices.

"As I write this, some 10 hours after the outage began, I don’t have many facts other than my Blackberry didn’t work for about 9 hours today," wrote blogger Matt Friedman on the .

AT&T did not respond to request for comment about the outage.