WARNING: DISTRESSING CONTENT

Two people were killed and 11 others wounded when a video game tournament competitor went on a shooting rampage before turning the gun on himself in the northern Florida city of Jacksonville.

David Katz, 24, has been identified as the suspect shooter at an online gaming tournament in Florida that was partially captured on a horrifying livestream.

Katz carried out his shooting rampage at the Jacksonville Landing complex at around 1.34pm on Sunday (local time), police said.

Jacksonville Sheriff Mike Williams confirmed that Katz is from Baltimore and had travelled to Jacksonville for the tournament.

He is also known by the gamer monikers 'Ravenschamp' and 'bread'.

Katz was armed with a semi-automatic and his car was seized by police near the scene.

Williams could not confirm if Katz knew any of the victims.

David Katz named as the gunman that opened fire on Sunday during an online video game tournament that was being livestreamed from a Florida mall. Photo / supplied

According to Steven "Steveyj" Javaruski, one of the competitors, the shooter was a gamer who was competing in the tournament and lost.

The shooter "targeted a few people" and shot at least five victims before killing himself, Javaruski told The Los Angeles Times in a direct message on Twitter.

He later tweeted police escorted him out of the venue.

I got out. Police escorted me. I’m done going to any Madden events not EA Majors with security.

— Noble SteveyJ (@ImSteveyJ) August 26, 2018

Last February, David Katz won the Madden 17 Championship. A tweet shared by the Buffalo Bills American football team shows him posing with a 'Madden Champ' shirt. Photo / Twitter

The riverfront mall in Jacksonville that was hosting the video game tournament. Photo / AP

Sheriff Williams said federal authorities raided a house at South Baltimore as part of the investigation into the shooting.

He appealed for anyone with videos or information of the incident to contact the Sheriff's Office.

Earlier dozens of ambulances and police cars flooded into The Jacksonville Landing within two minutes of a call, a waterfront dining, entertainment and shopping site in the city's downtown, after several shots rang out on a sunny Sunday afternoon (local time).

The shooting took place during a regional qualifier for the Madden 19 online game tournament at the GLHF Game Bar inside a Chicago Pizza restaurant, according to the venue's website.