Interpol’s website went down Tuesday, Feb 28, just hours after the international police agency announced the arrest of 25 suspected members of the hacking collective Anonymous in Argentina, Chile, Colombia and Spain, The New York Times reported.

On Twitter, hackers affiliated with Anonymous took credit for the attack and openly encouraged their sympathizers to keep Interpol’s site offline by flooding its servers with traffic.

The attack followed Interpol’s announcement Tuesday that it had arrested suspected Anonymous hackers in an operation it titled Operation Unmask. With cooperation from authorities in Argentina, Chile, Colombia and Spain, Interpol said it seized 250 pieces of technology equipment and mobile phones at 40 premises across 15 cities. Interpol said authorities had seized credit cards and cash from the some of the hackers, which spanned the ages of 17 to 40.

Interpol said it first launched the operation in mid-February following a series of coordinated cyber attacks against Spanish political parties’ Web sites, Colombia’s defense ministry and presidential Web sites, Chile’s national library, Endesa, a Chilean electricity company, and other targets.

The same hackers who claimed credit for bringing down Interpol’s site on Twitter also recently claimed credit for an attempted attack on a Vatican Web site last August that ultimately proved unsuccessful.

The arrest follows a string of increasingly bold attacks by Anonymous. Earlier this month the group knocked the CIA website offline. A week earlier, the group intercepted a conference call between the Federal Bureau of Investigation and Scotland Yard and released a 16-minute recording of the call. Since then, hackers affiliated with Anonymous even threatened to “shut the Internet down on March 31” by attacking servers that perform switchboard functions for the Internet.

As of Tuesday evening, Interpol’s site was still down.