Ain Jacksonville, Florida, with the Jacksonville Sheriff's Office so far reporting three fatalities including the suspect and 11 injuries resulting from the shooting.
The suspected shooter, believed to be 24-year-old David Katz from Baltimore, is dead at the scene, Jacksonville Sheriff Mike Williams said during a news conference, adding that authorities didn't believe there were any additional suspects.
One player, known as Young Drini, who was at the tournament, tweeted about being thankful for his life after being grazed in the thumb during the shooting. "I will never take anything for granted ever again," he wrote.
Social media quickly flooded with prayers, thoughts and condolences in reaction to the news.
Joey Cuellar, head of the Evo fighting game championships, announced on Twitter that his organization will be stepping up security at future events.
CBS News tweeted out a video interview with a contestant heading to the competition.
More esports and video game organizations also offered their condolences to the tragic news.
Professional fighting gamer Justin Wong tweeted condolences in reaction to what happened.
The NFL issued its own statement of condolences for victims and supporting EA Sports.
Former NFL quarterback Tim Tebow sent out prayers for Jacksonville, his hometown.
And many other people offered general thoughts and prayers on Sunday, including a #PrayerForJacksonville hashtag.
Editors' note: This article was first published Aug. 26, 2018 at 2:19 p.m. PT and is updated frequently as more reactions and statements are issued.
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