A bug in the Twitter made the list of followers and followed were zeroed out in the afternoon of Monday for no apparent reason. This left all service users unable to send direct messages to each other, were as the Twitter database they not following anyone.
Still, the timeline for all users continued to show tweets from whom they followed. The list function, and the official retweets, was not affected.
The company not yet posted none the following notice in the official blog service status: the bug is already fixed and functions of followers and followed should return to work soon.
[Updated at 14:10]: According to a message posted on the official Twitter account on Twitter (!), The role of followers and followed is off while they fix a bug still unidentified.
[Updated at 14:13]: Gizmodo discovered what was the bug. Apparently, it was possible to force anyone to follow you to post the message “accept [username]” the web version of the service.
[Updated at 15:03]: The numbers of followers and followed have reappeared.