Google’s mail and application services were unavailable to some users Wednesday morning. The company said it was investigating the problems, but didn’t know their cause. It didn’t say how many people were affected.

The disruptions started affecting people worldwide around 8 a.m. Eastern time but appeared to be resolved by midday.

Earlier, Google Inc.’s apps status dashboard showed that its Mail, Drive file storage service and office-application services were “disrupted.” Its administrator control panel, which lets companies manage their Google applications, was completely down.