The Library of Congress has fought off a massive cyberattack, officials confirmed Wednesday.

In a blog post, Bernard Barton, the Library’s Chief Information Officer, explained that the denial of service attack began on Sunday morning and disrupted a number of services and websites, including Congress.gov, the U.S. Copyright Office and the BARD (Braille and Audio Reading Download) service from the National Library Service for the Blind and Physically Handicapped. The attack also impacted Library databases and incoming and outgoing email, according to Barton.

The Library’s networked services are back to normal after the attack, which the CIO described as “a massive and sophisticated DNS assault, employing multiple forms of attack, adapting and changing on the fly.”

Barton’s post did not reveal any information on the attackers, but the noted that the Library has turned over “key evidence to the appropriate authorities who will investigate and hopefully bring the instigators of this assault to justice.”

A hacking group that goes by the name of Turk Hack Team reportedly claimed credit for the attack on an online message board.

The Library of Congress will remain on its guard against future attacks. “We’re satisfied that we’ve fended off the attack and fortified our system for now, but we’ll continue to be vigilant and employ state-of-the-art security systems to effectively respond to these type of incidents in the future,” said Barton, in the blog post. “This is not the first time that a large agency or organization has been targeted with this kind of denial of service, and it certainly won’t be the last.”

Cybersecurity expert Peter Metzger, who is vice chairman of executive search firm DHR International, told FoxNews.com that the Library of Congress attack highlights the ongoing threat posed by hackers. “This most recent attack is yet further evidence of a complex web of threats that are capable of sophisticated, sustained attacks against both soft and hard targets,” he said, via  email.

Distributed denial of service (DDoS) attacks, which often occur when a hacker “floods” a network with information, are a popular method for disrupting websites and services. Network specialist Akamai, for example, recently reported a 125 percent increase in DDoS attacks during the first quarter of 2016.

Government networks are frequently targeted in cyberattacks. Last year hackers based in China were suspected to be behind a huge breach that compromised data from the Office of Personnel Management (OPM) and the Interior Department. The attack came hot on the heels of a major IRS security breach that compromised tax information from more than 100,000 U.S. households.

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