International authorities last week arrested 34 individuals – mostly adults under 20 years old – who allegedly were using distributed denial of service (DDoS) tools to flood targets with malicious traffic, Europol announced on Monday.

The law-enforcement operation, which took place from Dec. 5-9, was a collaborative effort between Europol and 13 participating countries: Australia, Belgium, France, Hungary, Lithuania, the Netherlands, Norway, Portugal, Romania, Spain, Sweden, the UK and the U.S.

The young suspects are accused of paying for DDoS services commonly referred to as stressers and booters. In addition to the 34 who were arrested, an additional 101 suspects were interviewed or received warnings.

The operation took place as Europol and its European Cyber Centre (EC3) kicked off a campaign to raise awareness around the risks of young adults getting involved in cybercrime. “Many IT enthusiasts get involved in seemingly low-level fringe cybercrime activities from a young age, unaware of the consequences that such crimes carry,” said Steven Wilson, head of the EC3, in a Europol release. “One of the key priorities of law enforcement should be to engage with these young people to prevent them from pursuing a criminal path, helping them understand how they can use their skills for a more constructive purpose.”