Build-a-Bear's one day sale was so successful it was shut down — in some places, just hours after it began.

The company sent out the following message before noon Thursday:

"Please be aware: Based on the unprecedented response to our Pay Your Age Day event in our early opening stores, we are experiencing significantly longer than expected lines and large crowds. Local authorities are requiring us to limit the lines and crowds due to safety concerns. We understand this is disappointing, we are working to address the situation, and we will be reaching out to our valued Guests soon."

Livid parents took to social media in the U.S. and the U.K. to rage.

'Overwhelming and unprecedented'

Lines stretched outside Build-a-Bear's stores forever with parents reporting waiting up to six hours to buy a plush toy, according to some social media reports.

Build-a-Bear representatives called the promotion in a news release to All the Moms "overwhelming and unprecedented."

"The response to our Pay Your Age Day event has been overwhelming and unprecedented in our 21-year history, and the safety of our Guests and associates is our top priority."

Customers should hear something ASAP

The company said it is "working to address the situation" and "will reach out directly to our valued guests as soon as possible."

To earn the Pay Your Age promotion, adults had to enroll in the free Build-a-Bear Bonus Club rewards program and provide an email address.

Build-a-Bear is expected to contact customers through their email.