Update at 4:30 p.m.: Microsoft has confirmed through Twitter that Xbox Live is up and running again.
Update at 4:23 p.m. ET: It appears any issues with logging into Xbox Live may have been fixed, based on the latest update from Xbox Support.
Microsoft has just removed any mention of login errors from its Support page, only noting problems using the Click to Chat feature on the Support site.
I've been able to log in to my Xbox Live account through their website with no trouble. However, I can't confirm whether it's possible to do so through the Xbox 360.
Readers, able to log on now? Let us know.
Our original post
Microsoft is investigating an outage plaguing the Xbox 360 online service Xbox Live.
According to an update on their Support page, users are reportedly having issues signing in to Xbox Live from their console or through the primary Xbox website.
"We are aware of the problem and are working to resolve the issue. We apologize for any inconvenience this may cause and thank you for your patience," reads a statement on their Support page.
It's not clear how long Xbox Live has been down for users. The first responses from Xbox support to affected users were posted more than an hour ago, according to the official Xbox Support Twitter feed.
Mike Snider began covering the video game industry during the Super Nintendo-Sega Genesis clash in 1992. An original pinball wizard, he eventually was seduced by Robotron: 2084 and Tempest. These days he is a fan of action/shooters and lives out his Keith Moon fantasies playing a mean drum kit on music games. More about Mike.
Brett Molina has been writing about video games for USA TODAY since 2005. He is well-versed in Madden NFL, the fighting genre and first-person shooters. The first video game he played was Asteroids at a local arcade. He has been hooked ever since. More about Brett.