Almost 20 years after Pokémon came to North America, the franchise’s newest release is becoming an increasing concern for police.

In an advisory issued this morning, a New Jersey police department warned citizens to keep their wits about them while playing Pokémon Go to avoid falling victim to criminals.

“Please be aware of your surroundings and always use best practices for personal safety no matter where an app tells you to go,” West Windsor Police Lieutenant Garofalo wrote in the advisory. “That rare Pokémon may come at the cost of your car or possibly your life."

Pokémon Go is a smartphone game in which users hunt for cartoon monsters from the popular TV and video game series. Players must travel to various (and often unfamiliar) real-world locations in order to progress. The game’s popularity has exploded since its release in the United States and several other countries last week.

So far, Pokémon Go players throughout the country have stumbled upon a dead body, faced trespassing warnings and fallen victim to thieves.

“I actually downloaded it myself, just to see what was going on,” Garofalo told ABC News in a phone interview. “I caught a Pokémon in the police station to get an idea of what these people are doing.”

Garofalo said that he has had to warn officers that people who are seen acting bizarrely or wandering in strange locations may just be playing the game.

“If someone is in the park late at night, this is probably the reason why,” he said. “They’re not necessarily trying to smoke or do anything illegal.”

While he said is not worried about criminal incidents in his town, Garofalo advised Pokémon Go players to use common sense.

“Don’t do anything that you normally would think is bad,” he said. “Normally you wouldn’t go to a deserted alley at 3 a.m. That shouldn’t change just because an app said you should.”