Police searched on Monday for a motive in the third mass shooting in Florida in two years, which left two people dead and 11 wounded in Jacksonville, before the gunman killed himself at a video game tournament.
While police have not identified the victims, family members told Jacksonville CBS television station WJAX that the two people killed were Eli Clayton and Taylor Robertson, both were video game contestants.
The Miami Herald also identified the victims: Robertson, 27, of Ballard, West Virginia, and Clayton, 22, of Woodland Hills, California.
Robertson, a husband and father, was the winner of the tournament last year and Katz won it the year before, the Herald reported, citing family and friends posting on the Internet.
The Jacksonville Sheriff's office said 11 other people were wounded by gunfire and at least two others were injured while fleeing the scene of Sunday's shooting.
Police say Katz killed himself and his body was found near the bodies of the two shot dead at The Landing, a popular riverside shopping and restaurant spot in Jacksonville.
Jacksonville Sheriff Mike Williams declined Sunday to comment on possible reasons for the attack.
Police and FBI agents swarmed Katz's upscale townhouse in South Baltimore late on Sunday, multiple media accounts said, including the Baltimore Sun.
Police also seized Katz's vehicle parked nearby the tournament site.
The shooting took place during a regional qualifier for the Madden 19 online game tournament at the GLHF Game Bar inside a pizza restaurant, according to the venue's website.
The winners of the contest go forward to the video game finals in Las Vegas and compete for $165,000.
The latest rampage occurred amid a debate over U.S. gun laws that was given fresh impetus by the massacre in February of 17 people at a high school in Parkland, Florida.
Two years ago a gunman killed 49 people at the Pulse nightclub in Orlando.
Game LivestreamedThe bar was livestreaming a football video game competition when the gunfire started, according to video shared on social media. In the video, players can be seen reacting to the shots and cries can be heard before the footage cuts off.
Taylor Poindexter and her boyfriend, Marquis Williams, had traveled from Chicago to attend the tournament, and they fled when the gunfire erupted. She said she saw Katz take aim at his victims.
"We did see him, two hands on the gun, walking back, just popping rounds," Poindexter told reporters. "I was scared for my life and my boyfriend's."
Another gamer, Chris "Dubby" McFarland, was hospitalized after a bullet grazed his head. "I feel fine, just a scratch on my head. Traumatized and devastated," he wrote on Twitter.
The sheriff's office said many people were transported to hospital, and its deputies found many others hiding in locked areas at The Landing.
A spokesman for Jacksonville's Memorial Hospital said it was treating three victims, all of whom were in stable condition. The conditions of other patients was not available early Monday.
Reacting to news of the shooting during the tournament involving its game, Madden 19 maker Electronic Arts Inc said it was working with authorities to gather facts.
"The tragic situation that occurred Sunday in Jacksonville was a senseless act of violence that we strongly condemn," a company spokesperson said to Reuters late on Sunday. "Our most heartfelt sympathies go out to the families of the victims whose lives were taken today and those who were injured."