Twitter said Tuesday that its service was down for most users, both on the desktop as well as most mobile apps.

"Most users are experiencing issues accessing Twitter on web and mobile apps. We're looking into it," the company said on its status blog shortly before 11:30 AM PT. When trying to access Twitter, users reported server errors when trying to post updated tweets to their timeline. 

Twitter has largely moved away from the "fail whale" outages of several years ago, but the company has suffered brief outages--that, to its credit, the service has reported--in the last several months. On Jan. 28 and March 2, for example, the company reported "brief" outages that affected a minority of users. 

Twitter, of course, has far more money to throw at the problem than in the early days of the service. In November, YiYing Lu, whose "Lifting a Dreamer" later became the iconic Twitter "fail whale" image, crafted a new piece of art to commemorate Twitter's initial public offering: the "IPO Hippo".

The difference between the earlier outages and Tuesday's issues is that Twitter previously said the outages affected "some" users. On Tuesday, "most users" were affected. That would seem to indicate a more serious problem, one that Twitter said it's working to solve. We'll update this story as Twitter provides more information.

At press time, Twitter's share price was $54.55, up just over 1 percent from yesterday's close, and down from of a high of over $73 around last Christmas. Separately, The Verge reported that Twitter hired Baljeet Singh from YouTube to sell video advertising and improve the number and quality of the videos on Twitter.