According to a report from the Japan Times (via Polygon), a 9-year old boy was struck by a truck driver who was playing the game while he was driving, which meant that he did not see the boy as he was crossing the street. The driver has since been arrested where he had also confessed that he typically keeps the app open while he drives. The boy was sent to a hospital where he died 2 hours later.
In light of this accident, the country’s Ministry of Transportation tweeted a message that said (according to Google Translate), “Yesterday, fatal traffic accident that elementary school students meet the damage has occurred in Ichinomiya. Elementary school children in spite of had across the crosswalk, I had a victim. Life lost is not anymore return. But there shall be no such an accident again. Of drivers you, please drive to see the firm before!”
They also implored people to stop using their phones while driving. To Niantic’s credit, the developer has tried to stop players from playing while driving, such as by releasing warning messages if it detects players are playing the game while driving. A more recent update prevented Pokemon from spawning if the game was running while in a car, but if anything this incident reveals that maybe such measures aren’t quite as effective as they should be.