(CNN) The suspect who opened fire during a Madden video game tournament in Jacksonville, Florida, on Sunday actively targeted other gamers in his shooting spree, Sheriff Mike Williams said.

The shooting left two people dead, 10 injured from gunshots and one person with a non-gunshot injury, Williams said. All of the injured are expected to survive, he said.

"As bad as this is, it could have been much worse," Williams said.

Katz's motive in the shooting remains under investigation, police said. The suspect had legally purchased two weapons in Baltimore over the past month, and one of the weapons had a laser sight that attached to the gun, officials said.

Alexander Madunic, a gamer who was shot in the foot, said the shooter lost a game in the Madden tournament earlier in the day and was angry.

"He was kinda upset about that, so I'm guessing that had something else to do with it, too," Madunic said.

Confusion, chaos and bloodshed

JUST WATCHED Hear the moment tournament shooting happened Replay More Videos ... MUST WATCH Hear the moment tournament shooting happened 02:30

Fans followed an online stream of the event, posted on the website Twitch. The game abruptly stopped after several gunshots rang out

One person cried out, "Oh f***, what'd he shoot me with?"

Tony Montagnino told ABC's "Good Morning America" he was the shooting victim who shouted those words.

"My first reaction, I heard the shots and I thought, 'Why is there firecrackers in here?' " Montagnino said Monday.

"And then I actually got hit. And I've never been shot before. So I didn't know what to think. And then I turned around and actually saw the flashes from the gun. And at that point (I) just went into survival mode, and I just wanted to make sure I was out of there."

Ryan Aleman said he huddled in a bathroom for 10 minutes before running for his life.

"I'm still shocked, I can hardly talk," he told CNN.

Two people were injured fleeing the area, the sheriff said.

The Jacksonville Sheriff's Officer identified the victims as Eli "trueboy" Clayton, 22, and Taylor "SpotMePlzzz" Robertson , 27. Both were competitive Madden players, and Robertson had won the Madden Classic tournament in 2017.

On Monday, Memorial Hospital released the names of four surviving victims it treated:

-- George Amadeo II, 17, is in good condition.

-- David Echevarria, 28, was treated for minor injuries and released.

-- Alexander Madunic, 27, is in good condition after a gunshot wound to the foot.

-- Christopher McFarland, 31, is in good condition after a bullet graze to the head.

UF Health said four patients were discharged, but two others remain hospitalized. One is in serious condition and one is in good condition, the hospital said.

Timothy Anselimo's mother tweeted a photo of Gov. Rick Scott visiting the wounded gamer at his hospital bed.

The governor of Florida with my son @oLARRY2K pic.twitter.com/nP0VCLUyYY — Sujeil (@olarrysmom) August 27, 2018

President Donald Trump expressed sorrow for the victims in remarks before an evangelical leadership dinner at the White House on Monday.

"I want to extend our prayers and condolences to the victims of the tragic shooting in Jacksonville, Florida," the President said. "That was a terrible thing indeed. How it happens, nobody really knows."

Gunman said in 2017, 'I'm one of the better players'

Hours after the shooting, agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives and FBI and Baltimore Police searched Katz's family home in Baltimore.

Katz went by the gaming naming "Bread" and previously won Madden tournaments in 2017, multiple gamers told CNN.

In February 2017, the Buffalo Bills tweeted out a picture of him after he won the Madden 17 Bills Championship. "Congrats to David Katz, the Madden 17 Bills Championship winner! Thanks for following along, Bills fans," the tweet read.

Suspect David Katz in 2017 when he won tournament.

In an interview after the win with former Buffalo Bills player Steve Tasker, Katz talked about his prowess.

"I think personally I'm one of the better players," he said.

Katz was previously a student at the University of Maryland, according to university spokeswoman Katie Lawson. Katz was enrolled beginning in September 2014, but he was not registered for classes as of August 26, 2018 and did not live on campus, Lawson said.

Katz underwent treatment for psychological and emotional issues, according to his parents' divorce records obtained Monday by CNN.

He was once placed on an antipsychotic medicine used to treat schizophrenia. His father, Richard Katz, objected, saying he "has seen no evidence whatsoever of schizophrenia in David Katz. David seems well aware of reality at all times."

The alleged gunman was also placed on two antidepressants, which his father said at the time "pose significant and unknown risks to the children."

The 2006 filing was part of a divorce and custody battle that was so acrimonious, both parents filed to have a guardian ad litem assigned to David, who was 12 at the time.

Both Elizabeth and Richard Katz are cooperating with investigators and have told authorities that their son had mental health issues, a source told CNN.

David Katz's parents could not be reached by CNN for comment on Monday.

Another mass shooting in Florida

"We have got to change," Gov. Rick Scott told reporters Sunday night. "We've got to really stop and say to ourselves: there's something wrong."

"Why are young men willing to give up their life, or why don't they value somebody else's life?" he said. "We've got to figure this out."

Former Congresswoman Gabrielle Giffords, who was seriously wounded in a mass shooting, said the nation's attention turns to Florida, again.

"The nation once again looks to Florida with grief and heavy hearts," Giffords, who co-founded a gun violence prevention organization , said in a statement.

"The massacre in Jacksonville is a tragic reminder of the threats we face from gun violence, no matter who we are or where our day takes us," said Giffords. "And it's yet another devastating indictment of this country's inability to keep our kids safe."

The nation once again looks to Florida with grief and heavy hearts. The massacre in Jacksonville is yet another devastating indictment of this country's inability to keep our kids safe. https://t.co/NNw88rVWR2 — Gabrielle Giffords (@GabbyGiffords) August 26, 2018

EA Sports, a video game developer and publisher, condemned the shooting as "a senseless act of violence."

CompLexity Gaming founder and CEO Jason Lake told CNN that the shooting may make the growing eSports industry reconsider security at events.

One of the company's gamers, a 19-year-old who goes by Drini, was shot in the thumb but managed to escape and is going to be fine, Lake said.

"To have someone walk into an event like this that's all about good sportsmanship and teamwork and just good vibes, and do something like this, it's heartbreaking," he said. "I think the e-sports industry as a whole is going to have to step back and take a look at further strengthening our security."