Four Hong Kong teenagers have been arrested in connection with nine cases of “hacking” game machines at various branches of a popular indoor arcade chain, allegedly collecting HK$20,000 worth of prizes.

The group of three boys and a girl allegedly bought wireless devices online and used them to tamper with at least nine game machines at four branches of the chain, which the Post learned was Jumpin Gym USA.

The chain called police earlier this month after spotting suspicious operations of some prize machines at various branches.

Senior Inspector Lam Nga-sze of the New Territories South regional crime unit said: “The gang members had divided themselves into different clear roles. One of them bought the jamming device online and committed the crime.

“They usually went during non-peak hours when there were fewer customers. One of them would get near the game machine and use the wireless equipment to interfere with the operation of the game machine.

“The other gang members would pretend to use the game machines nearby as a cover and pay attention to whether there were any staff getting close.

“They got free plays without having to insert tokens, and no matter what, the machines would pour out the prizes or game cards.”