Who is David Katz, alleged Jacksonville mass shooter

A Baltimore man fatally shot two people and injured nine others Sunday during a video game tournament in Jacksonville, investigators said.

David Katz, 24, then turned the gun on himself, Sheriff Mike Williams said.

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Although witnesses have said he was angry about the tournament, Williams did not give a motive as to why Katz started shooting at 1:34 p.m. during the Madden Championship Series competition at the Good Luck Have Fun Game Bar, at the Jacksonville Landing, a popular riverfront destination.

Williams did confirm that Katz was in town for the two-day tournament, but did not say if he was a competitor.

A witness said Katz lost an intense game, snapped, and started shooting.

Dennis Alston, who was a video game competitor, said he beat Katz Saturday when they played. When he tried to shake his hand after losing, Katz stared blankly back.

Katz is a 2017 championship winner, according to EA Sports.

Williams confirmed that federal investigators are searching Katz's Baltimore residence.