Should be fixed now. Working to understand why it happened — jack (@jack) October 16, 2018

Shortly after people began reporting the odd notifications, and, naturally, wondering what exactly was going on, CEO Jack Dorsey tweeted that the company was "on it." Minutes later, he added that the issue was fixed and Twitter was working on figuring what happened. We've reached out to Twitter and we'll update this post if we hear anything more.

Update 10/16/18 2:20PM ET: Twitter support has shared some additional information about the mishap. In a tweet, it said that the alphanumeric strings were basically the code Twitter uses to talk to your phone. It reiterated that the problem is now fixed.