A 20-year-old man, Calvin Riley, who was a baseball pitcher in his school was shot and killed on Saturday while playing Pokemon GO at a tourist attraction in San Francisco, along the city’s waterfront. Riley was playing Pokémon Go on Saturday night with his friend at Aquatic Park near Ghirardelli Square, U.S. Park when he was shot in the back by an unknown gunman Police said.A family friend, John Kirby told KGO-TV:

"From what we know there was no confrontation. There was nothing said back and forth. It was just senseless, just came up and shot in the back and ran away for nothing,"Kirby said Riley and his friend had noticed someone was watching them from the top of a hill that overlooks the park.

However, it was dark and they were mostly focused on their cellphones so they barely paid any attention to the person.

National Park Service spokesman Lynn Cullivan said investigators believe there are witnesses to the attack because it happened in the bustling Fisherman's Wharf area.

Sgt. Robert Jansing, a detective with the U.S. Park Police, said the gunman did not take any of Riley's belongings or try to rob him wither.

It's unclear whether the attack had anything to do with Pokemon GO, which has become a US national s£nsat!on this summer as legions of fans visit real-world landmarks in order to find and trap cartoon creatures.

Law enforcement officials have warned about the game's possible dangers, saying players can become engrossed in the game and tune out to their surroundings.