PHOENIX — The “Pokemon Go” craze across the U.S. has people wandering into yards, driveways and cemeteries in search of cartoon monsters, prompting warnings that trespassers could get arrested or worse, if they cross paths with an armed property owner.

Since the release of the smartphone game last week, police have gotten a flurry of calls from residents about possible burglars or other strangers prowling the neighborhood.

So far, few tickets have been issued, and there have been no reports of arrests or assaults on trespassers playing the game, whose object is use the phone’s GPS technology to find and capture animated creatures in real-world places.

“Be careful where you chase these Pokemon – or whatever it is you chase – because we have seen issues in other places with people going onto private property where a property owner didn’t want them on there,” said Assistant Police Chief Jim McLean in Pflugerville, Texas.

Some players have expressed worries on social media that the game could result in a fearful property owner pulling a gun – a scenario that could fall into a legal gray zone in the nearly two dozen states with “stand your ground” laws.

McLean’s department posted a Facebook warning Monday after officers spotted a man playing the game in a section of a police parking lot where the public isn’t allowed. The player had to pass keep-out signs and go over a fence or under a gate to reach the area.

“I’m not sure how he got back there, but it was clear what he was doing,” McLean said. “He was playing a Pokemon game with his phone up in the air.”

In Utah, Ethan Goodwin, 17, of Tremonton was given a trespassing ticket that he worries could cost him up to $200 after he and a couple of friends went on an early morning Pokemon chase at an abandoned warehouse. He managed to catch three creatures.

“I wouldn’t say it was worth it, but I would say I’m glad I have the Pokemon I have now,” he joked. He added: “It’s a dumb game, really, really stupid.”

Every time the app is opened, a warning from game maker Niantic pops up, telling players to be aware of their surroundings. Players must also agree to fine print saying they cannot enter private property without permission.

There’s also a disclaimer that says Niantic is not liable for any property damage, injuries or deaths that result while playing.

But those warnings don’t seem to be getting through.

In Phoenix, police have started posting humorous and colorful warnings on social media, saying chasing the orange dragon Charizard is not a valid reason to set foot on someone else’s property.

And neither is chasing the cat-like Mewtwo, according to Boise, Idaho, police. They posted a Facebook message saying officers responded to several calls about players trespassing.

Gamers are also being warned to watch for traffic while playing and not to drive while on the app.

A woman in western Pennsylvania said that her 15-year-old daughter was hit by a car while playing the game and crossing a busy highway. The girl was hospitalized with an injured collarbone and foot, said her mother, Tracy Nolan.