(NEXSTAR) -- The Internet Archive, a popular digital library known for its Wayback Machine, was hacked and suffered a data breach that reportedly exposed 31 million user accounts.

Founder Brewster Kahle confirmed in a post on the social media platform X that a cyberattack on Tuesday knocked the website offline. He also said that usernames, emails, and encrypted passwords had been compromised.

"Services are currently stopped to upgrade internal systems," Kahle wrote in a Thursday update. "We are working to restore services as quickly and safely as possible. Sorry for this disruption."

He explained that hackers launched a Distributed Denial of Service (DDOS) attack against the library. This type of attack floods a website with excessive traffic, causing it to crash or become inaccessible, according to the Cybersecurity & Infrastructure Security Agency.

Forbes reported that users realized something was wrong when a strange message popped up on the Internet Archive's website earlier this week: "Have you ever felt like the Internet Archive runs on sticks and is constantly on the verge of suffering a catastrophic security breach? It just happened. See 31 million of you on HIBP!"

HIBP, short for "Have I Been Pwned," is a website that allows users to check if their personal info, such as email addresses and passwords, has been exposed in a data breach.

Although hackers disrupted access to the Internet Archive this week, security expert Troy Hunt, who created HIBP, said on X that the actual data breach likely occurred more than a week ago.

Hunt said he first received information about the breach on Sept. 30 but didn't get a chance to analyze it until Oct. 5. He then notified the Internet Archive and updated the HIBP site, which shows more than 31 million accounts have been compromised.

Additionally, Hunt suggested that "multiple parties" might be involved in the recent disruptions, noting that "when we're talking breach + defacement + DDoS, it's clearly not just one attack."

For those unfamiliar, the Internet Archive is a non-profit that was established in 1996 and provides free access to millions of videos, books, audio files, and photos. Its Wayback Machine captures snapshots of websites over time and lets people view older versions of them.

Kahle said the Internet Archive has scrubbed its systems and upgraded its website security in the wake of the recent cyberattack. The site was still down as of 5:30 p.m. CT Thursday.

Nexstar has reached out to the Internet Archive for comment.