Gmail service for users of the Google for Work cloud-based productivity suite was down for over 12 hours on Wednesday, apparently affecting users in a number of countries including the U.S.Google reported early Thursday that the problem was resolved for the vast majority of affected customers, and it would be working individually with the rest of them. It said it would provide a more detailed analysis of the incident to customers once its internal investigation is completed.The company first acknowledged the problem on its Apps Status Dashboard at 8:16 a.m. Pacific Time on Wednesday, stating that it is investigating reports of an issue with Gmail. \u201cBased on reports, it affects only Google for Work Gmail users," Google said. Affected users were redirected to a page with 'Service not available, contact your administrator.'The company reported soon after that it had identified the root cause of the issue and was implementing a potential fix. Google subsequently said that the Gmail service had already been restored for some users, and at one point said it expected a resolution for all users in the next one hour. In later posts it dropped the promise of a resolution for all users in one hour, suggesting that the problem could be more serious.[ ALSO: 7 ways to avoid alert fatigue ]\u201cPlease note this time frame is an estimate and may change. Delivery of messages sent to affected users during the issue may be delayed,\u201d it said in these subsequent messages.When contacted for information on the issues involved and how long the disruption was expected to last, Google\u2019s press team referred to the Apps Status Dashboard for the latest information. A number of users reported they were affected. \u201cGmail is down & I work as a freelance writer & am I law school. You can imagine how my night\u2019s going,\u201d wrote a user in Pittsburgh, Pennsylvania, who said she had to apologize to clients but couldn\u2019t do that either.Purple Dog Design, a web design and e-marketing company in New Zealand for small and medium enterprises, said a number of its clients were affected in the U.S., Australia and New Zealand. The Idaho Statesman said late Wednesday that widespread Gmail outages in the U.S. and U.K. left many of its editorial, circulation and advertising staff unable to access their accounts.