"All public tickets are first-come, first-served, including those sold tonight," the ticketing giant said in the email, adding that "a significant number of public tickets were purchased this evening."
The botched sale earned the company and inaugural committee considerable ire on social media, later aggregated in a post by BuzzFeed.
Officials for the inaugural committee issued a statement Monday pointing the finger at Ticketmaster for the error.
"On Sunday evening, Ticketmaster experienced a technical error that inadvertently caused an email to go out ahead of schedule to people who had signed up for Inaugural ticketing information with an invitation to purchase public tickets for The Inaugural Ball and the Inaugural Parade," the committee said in a statement. "The Ticketmaster website was overwhelmed, slowing the purchasing process. Ticketmaster has taken responsibility for this mistake."
This post was updated at 10:50 a.m.