SAN FRANCISCO (AP) — A 20-year-old man was shot to death while playing “Pokemon Go” at a tourist attraction along San Francisco’s waterfront, authorities and a family friend said.

An unknown assailant shot Calvin Riley on Saturday night at Aquatic Park near Ghiradelli Square, the U.S. Park Police said Sunday. A family friend called it a random attack.

Riley was playing the hit mobile game with a friend when someone shot him from behind and took off, John Kirby told KGO-TV.

“From what we know, there was no confrontation,” Kirby said. “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 watching them from the top of a hill that overlooks the park, but it was dark and they were mostly looking at their cellphones.

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. They are seeking tips.

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.

Riley graduated from high school in San Mateo and pitched for the baseball team at San Joaquin Delta College.

“It’s a huge loss to everyone,” the school’s head coach, Reed Peters, told KGO-TV. “He was a great kid, a great competitor.”

It’s unclear whether the attack had anything to do with “Pokemon Go,” which has become a national sensation this summer as legions of fans visit real-world landmarks in a hunt for digital creatures.

But the game’s popularity has created unintended consequences in everyday life.

Property owners complain of players trespassing or damaging their grounds, and scores of players have been injured or robbed as they stare at their phones and try to track cartoon monsters.

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

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