‘Pokemon Go’ is now the number one game in the Apple app store, but local Knoxville and Tennessee officials have warned players to play safely and legally after issues have occurred worldwide.

The game encourages users to walk around their homes, neighborhoods and surrounding areas to search for and 'catch' Pokemon that appear on their phone screens.

Knoxville Police said no users have reported crimes here yet, but they have received calls about people staying in public parks after hours to play the game, when they can 'catch' Pokemon that only come out at night.

“We have great city parks,” said KPD Public Information Officer Darrell DeBusk. “But they need to be cautious.”

The Tennessee Highway Safety Office issued a warning regarding a different threat the game has posed - using the app while driving.

“With the recent release of Nintendo’s Pokemon GO virtual gaming application, the Tennessee Highway Safety Office urges drivers NOT to engage in Pokemon catching behind the steering wheel,” the department said in a Facebook post. “Find other ways to play safely. Eyes on the road, Pokemon Masters!”

Other Knoxville organizations and departments have issued their own warnings.

Meanwhile, the game has exploded in popularity around the U.S. and the world.

But the game has already caused injury and led to crime.

People have taken to posting pictures on social media about how they’ve gotten injured from collisions as they walk around while focusing on the game on their smart phone.

A 19-year-old Wyoming woman found a body face down in a river while playing the game.

In a St. Louis suburb, two men used the game as a way to pinpoint potential victims to mug because they knew they would be distracted.

A police station in Australia has had to post warnings on Facebook asking people to stop trying to enter the station to catch a Pokemon that appears to be inside.