Despite some server problems caused by the sheer number of people trying to play it, Pokémon Go is proving incredibly successful. The augmented reality game is now installed on more US Android phones than Tinder (it's doing equally well on iOS) and is close to having more daily active users than Twitter. It seems, however, that some unscrupulous types have been taking advantage of Pokémon Go's dedicated fans.

Police in O'Fallon, Missouri, say that four men used the game to attract players and rob them at gunpoint. By setting up a lure at a Pokéstop and waiting for gamers to arrive, the thieves were able to rob 11 people in the counties of St. Louis and St. Charles.

The latest incident occurred around 2 AM on Sunday morning. Police responded to a robbery report that led them to four local residents, all aged 16 to 18, in a black BMW in a CVS parking lot. The suspects attempted to throw a handgun out of the vehicle as officers approached.

O'Fallon police sergeant Bill Stringer said: "Using the geolocation feature, the robbers were able to anticipate the location and level of seclusion of unwitting victims."

Three of the men have been charged with Robbery in the 1st Degree and Armed Criminal Action, and had a bond set at $100,000 cash. They have been named as Shane Michael Backer, 18, Brett William Miller, 17, and Jamine James D. Warner, 18.

The police department warned people to be cautious when using Pokémon Go. "If you use this app (or other similar type apps) or have children that do, we ask you to please use caution when alerting strangers of your future location."

This isn't the first time that Pokémon Go has made headlines for reasons other than its popularity. Police in Darwin, Australia, had to remind players that they didn't need to step into the local station to gain Pokéballs; and just this weekend, a teenager in Wyoming discovered a dead body in the river while trying to get a water Pokémon.