UPDATE: 4.15 p.m. EDT -- Speaking to International Business Times, a Facebook spokesperson said: "We’re currently restoring Facebook services that people had trouble accessing earlier today due to a configuration issue. We’re working to bring things back to normal for everyone. We apologize to those who have been inconvenienced."

Original story

Facebook is down for the third time in a month, for unknown reasons. DownForEveryoneOrJustMe is reporting the outage, while Google Trends has shown a sudden spike in searches for "is Facebook down."

This is the third time Facebook has gone down this month. The first time, on Sept. 17, led to a "Service Unavailable" message. The second time, on Sept. 24, users trying to log on were met with a banner saying "Something went wrong."

It's not clear at this stage what knocked the social network offline this time, but considering Facebook has over 1 billion users, the effects are sure to be widespread.

Facebook shares (NASDAQ:FB) were off 3.8 percent, to $89.24, in late-afternoon trading Monday.