Six UK teenagers have been arrested on suspicion of attacking websites with the help of Lizard Squad.
Lizard Squad claimed to have knocked the Xbox and PlayStation gaming services offline over Christmas.
The group set up a website letting paying customers use its Lizard Stresser tool to launch similar attacks.
None of the teenagers are believed to be Lizard Squad members, nor linked to the Christmas hack.
Lizard Stresser takes down servers and websites by flooding them with huge amounts of data - they're called distributed denial of service (DDoS) attacks.
The 15-18-year-olds are suspected of buying Lizard Stresser using alternative payment services, such as Bitcoin, to remain anonymous, and then maliciously deploying it.
The teenagers are believed to have targeted organisations including a national newspaper, a school, gaming companies and some online retailers, says the National Crime Agency (NCA).
It hasn't confirmed whether the attempted attacks were successful.
"By paying a comparatively small fee, tools like Lizard Stresser can cripple businesses financially and deprive people of access to important information and public services," said Tony Adams, from the NCA's National Cyber Crime Unit.
"One of our key priorities is to engage with those on the fringes of cyber criminality, to help them understand the consequences of cyber crime and how they can channel their abilities into productive and lucrative legitimate careers."
The teenagers haven't been named. Those arrested this week are:
- An 18-year-old from Huddersfield, West Yorkshire
- An 18-year-old from Manchester
- A 16-year-old from Northampton
- A 15-year-old from Stockport
Two other suspects, both 17, were arrested earlier this year. One is from Cardiff while the other is from Northolt, north-west London.
All six have been bailed.
Two other 18-year-olds - one from Manchester and one from Milton Keynes - were interviewed under caution.