There's a new reason to call it March Madness.

CBSSports.com, where fans fill out brackets for the NCAA basketball championship tournament, drove users crazy when the site crashed Thursday morning.

According to DownDetector, which tracks social media posts about connectivity issues, a flood of fans began reporting issues accessing brackets on CBSSports.com around 11 am ET.

That was just minutes before tipoff of the Notre Dame v. Princeton game in Buffalo.

"During the hour before the first tip, service was down due to overwhelming demand," CBS Sports said in a statement issued around 1 pm ET. "We certainly regret the outage but are pleased to say that service has since been restored."

The site appeared to be up and running again just after noon. But not before Twitter lit up with frustrated users.

Bracket making is a massively popular endeavor for basketball fans during the tournament. The American Gaming Association estimates that about 70 million brackets will be filled out this season.

Though CBS Sports isn't the only site that hosts brackets, it's a popular destination since CBS Sports and Turner Sports (which is owned by CNN parent Time Warner) are the primary broadcasters of the games.