Police said Friday they are looking into who is responsible for the service interruption of police and prosecuter websites in the Netherlands.

The websites were offline intermittently Friday morning. Some say the hacktivist group Anonymous is to blame, attacking the sites in response to the arrest of a 16-year-old for involvement with the hacking of Visa, Mastercard and PayPal sites.

Dutch media have previously reported that Anonymous was indeed responsible. But police officials backed away from attributing the site disruptions to hackers.