Photo-sharing site Flickr was down Tuesday night, preventing the site's users from uploading and browsing images.
It wasn't immediately clear how long the site had been offline or what the cause was, but the Yahoo-owned site's home page was replaced by a message saying it was aware of the problem and was working to resolve the issue.
CNET has contacted Flickr for more information and will update this report when we learn more.
In celebration of Yahoo Mail's 16th birthday, the Web portal on Tuesday, including a new desktop theme based on Flickr images.
Unplanned outages from technical problems -- some of which afflicted Flickr shortly after its -- remain a problem for many companies. Culprits there include hardware and software problems and network attacks.
Update at 8:50 p.m. PT: Flickr is back up.