The Jacksonville Sheriff's Office tweeted that there are multiple fatalities, with one suspect, a white male named David Katz, age 24, dead at the scene. In a press conference, Sheriff Mike Williams confirmed that there are no additional suspects. The shooting was committed using a single handgun. The shooter is from the Baltimore area, and Williams said the FBI are assisting investigations there. The Baltimore Sun reports that authorities were seen at a South Baltimore home.

In a second press conference, Williams confirmed that there were 13 known victims. Two were killed on site, nine were transported to local hospitals and of those, seven were treated for gunshot wounds. Two additional gunshot victims transported themselves to hospitals. All the living victims are in stable condition. The identities of the victims have not yet been revealed. Police are asking any other victims who self-transported to hospitals to contact them.

The shooting reportedly happened during a qualifying event for the Madden 19 Tournament, an American football video game by EA at Chicago Pizza. Shots were fired at 1:34 p.m. ET and officers were on the scene by 1:36.
The event was livestreamed on the gaming platform Twitch. While the video from the event has been removed, the New York Times reports that 12 shots were heard and a red laser dot was spotted on the shirt of a player. Williams asked any other onlookers with video or information about the shooting to reach out to the Jacksonville Sheriff's Office.
The Los Angeles Times spoke to Steven “Steveyj” Javaruski, a competitor in the tournament, who says the shooter was a gamer who lost the competition. According to Javaruski, he targeted a few other participants, shooting "at least five" before turning the gun on himself.
During the shooting, police advised the public to stay far away from the location, the Jacksonville Landing, and requested that people hiding in the mall to call 911 to and report their location so a SWAT team could find them. At the first press conference, Williams confirmed that police had cleared the location.