STORY: Ticketmaster canceled its general public ticket sales for Taylor Swift's upcoming U.S. tour.

The move came after complaints from fans about website crashes earlier in the week - and after a U.S. senator raised questions about the company's dominance.

Ticket presales for Swift's Eras tour in the United States -- her first tour in five years -- opened Tuesday.

But fans who rushed to buy them through Ticketmaster's website encountered long wait times and site outages, with many left ticketless in the end.

This ultimately led to the company tweeting Thursday afternoon that it was canceling Friday's public ticket sales due to "extraordinarily high demands on ticketing systems and insufficient remaining ticket inventory."

It was not immediately clear whether any more tickets would be sold.

After hearing the news, some took to social media, posting tweets that read:

"WHAT THE DAMN HELL?!! Are you kidding me Ticketmaster?!! Taylor Swift must be livid. This is insane. Get it together. She deserves better...every other artist does too. We ALL deserve better than you."

And:

"Swifties, rise up in protest!"

On Wednesday, in a letter to Ticketmaster parent Live Nation, Senator Amy Klobuchar, chair of the Senate antitrust panel, voiced "serious concern about the state of competition in the ticketing industry and its harmful impact on consumers."

Ticketmaster responded, saying it had anticipated heavy demand for Taylor Swift tickets, but that extreme interest, combined with bot attacks, led to "unprecedented traffic on our site" and inconvenience for some fans.

The company added that about 15% of interactions across the site experienced issues and that it sold 2 million tickets on Tuesday.