In a major hit against cybercriminals, an international police operation has taken down what investigators called the world’s biggest provider of potentially crippling Distributed Denial of Service attacks.

Police hailed the success of the operation Wednesday, saying that a joint investigation led by Dutch and British experts and supported by European Union police agency Europol led to the arrest on Tuesday of the administrators of the website webstresser.org.

Europol said webstresser.org had more than 136,000 registered users and racked up 4 million attacks on banks, governments, police forces and the gaming industry. Distributed Denial of Service, or DDoS, attacks attempt to make online services unavailable by overwhelming them with traffic from multiple sources.

“It used to be that in order to launch a DDoS attack, one had to be pretty well versed in internet technology,” Europol said in a statement. “That is no longer the case.”

The agency said that registered users could pay a fee of as little as 15 euros ($18) per month to rent its services and launch cyberattacks.

Administrators of the service were arrested Tuesday in Britain, Croatia, Canada and Serbia, Europol said. The illegal service was shut down and computers and other infrastructure seized in the Netherlands, the United States and Germany.

Gert Ras, head of the Dutch police’s High Tech Crime unit, said the operation should send a clear warning to users of websites like webstresser.

“Don’t do it,” Ras said. “By tracking down the DDoS service you use, we strip you of your anonymity, hand you a criminal record and put your victims in a position to claim back damages from you.”

(AP)