SAN JOSE (CBS SF) — San Jose police are seeing a change in the type of gambling operations being busted across the city. While gambling busts have become an annual event in San Jose every spring or summer, it appears criminals are evolving to try to stay one step ahead of investigators.

Gambling operations are hidden in plain sight at locations that appear to be typical strip mall businesses, such as a PC repair shop or a hair and nail salon. But if you look closely some things don’t add up. The businesses are heavily fortified and secured. Inside, there isn’t a workstation to be found, just a small waiting room with a door that leads to a more secure backroom.

And it’s in backrooms where police, with help from the feds, have found the gambling parlors. Five people have been arrested in the past year on suspicion of operating businesses as a front for illegal gambling, police reported. 51 illegal gambling machines at five different addresses were seized, retrieving about $75,000 in cash.

Two additional search warrants from the U.S. Department of Justice resulted in the seizure of 13 illegal gambling machines and $280,566 in cash, which authorities believe are proceeds from gambling.

This is the state of illegal gambling in San Jose, more sophisticated and harder to catch than ever before. According to police, the alleged gambling enterprises have had a “particularly adverse impact” on the city’s Vietnamese communities.

“Gangs and organized crime groups, they like this type of business because it’s extremely lucrative,” said San Jose Police Lt. Paul Messier.

After getting tips from the public, a judge issued search warrants. At one – a PC shop in east San Jose – investigators said there was a false wall, with fake computer merchandise, that hid a full-blown gambling operation. The crooks also had installed kill switches on the computers.

What’s more, they found several people who were gambling in a way they had never seen before..

“They were not at the location. There was an app that individuals were using on their phone,” said Messier. “They would come into the business, put credits on the books, then gamble on their phones.”

It wasn’t always this secretive. As recently as 2015, the gaming machines were out in the open, at Vietnamese coffee shops all over the city. Police have been raiding illegal operations every year now, netting dozens of machines and hundreds of thousands of dollars every year.

Police say the gambling is a cancer on the community. The gamblers themselves often go broke and then steal or commit other crimes to fuel their habit, and gangs extort businesses and attack each other over turf wars.

“So when we take these enforcement actions there’s a ripple effect to that,” said Messier. “And it’s a positive ripple effect. And it’s good for the community and bad for the gangs. And that’s what we want.”

San Jose police describe this operation as being like Whack-A-Mole, where you take one out and another one, or two, pop up to take its place. It appears the criminals may be taking advantage of the staffing shortages at the department, but with the SJPD hiring more officers, including in the vice unit, its expected such operations will increase in the coming months.