According to police, a participant in a video game tournament in Jacksonville, Florida, has shot and killed two people before killing himself. The killer has been named as David Katz, 24, from Baltimore, and he has been said to have used one hand gun. No other suspects are being investigated.
Alongside those that lost their lives, 11 more people were injured at Jacksonville Landing, a big shopping and entertainment complex.
Multiple unconfirmed reports have suggested that Katz became angry after losing at the American football eSports event.
Until their next-of-kin are told, the victims will not be officially named, although tributes to two gamers are beginning to appear on social media.
According to the Independent, people are questioning the level of security at the venue. One participant claimed to have seen no security screening at the entrance, and suggested that such considerations had failed to keep with the scale and seriousness of events such as this one.
In recent years, Florida has experienced several mass shootings, including at the Pulse nightclub in Orlando in 2016, when 49 people were killed, and at the Marjory Stoneman Douglas School in Parkland in February 2018, where a further 17 people lost their lives.
On Sunday, before the shooting occurred, participants were playing the American football game Madden NFL 19 at the GLHF Game Bar, located in Jacksonville Landing.
A video stream of the event being shown on the Twitch platform seems to display two competitors playing a game when a red dot appears on one of their sweatshirts, with gunfire then ensuing.
19-year-old Drini Gjoka, a participant in the competition, described the shooting in a series of tweets, deeming it 'the worst day of [his] life'. He also tweeted 'I am literally so lucky. The bullet hit my thumb'.
Another gamer, Chris "Dubby" McFarland, tweeted 'They took me to the hospital. Bullet grazed my head. I feel fine, just a scratch on my head. Traumatized and devastated.' He added that 'All the time you hear about these shootings and pray for everyone involved. Donate money. Raise awareness and do everything you can. But to be in the room getting shot at and seeing your friends dead......man'.
When the shooting started, people fled to find shelter, and the police requested that they remain calm as SWAT teams searched the premises for potential accomplices before verifying that only one gunman was involved.
Some reports in the US suggest that Katz was a well known gamer, going by the name of 'bread' or 'sliced bread', and has been victorious in at least one Madden championship in 2017. He was thought to have been staying in a nearby hotel.
The FBI confirmed that it had searched Katz's father's home in the Inner Harbour area of Baltimore on Sunday evening.
Taylor Poindexter from Chicago claimed she saw Katz taking aim at people in the room. She said 'We did see him, two hands on the gun, walking back, just popping rounds. I was scared for my life and my boyfriend's.'
Sheriff Mike Williams said that 'There were nine victims transported by JFRD [Jacksonville Fire and Rescue Department] to area hospitals. Some of those have gunshot wounds. There were two additional gunshot victims that self-transported themselves to local hospitals'.
Jacksonville Mayor Lenny Curry stated that 'Tonight, Jacksonville is mourning. We've faced an occurrence that is all too common that will require us to continue to do the hard work of public safety.
EA Sports, the company that owns Madden and authorised the competition, told the BBC that it was 'devastated by this horrific event... a senseless act of violence that we strongly condemn'. It tweeted that 'This is a horrible situation, and our deepest sympathies go out to all involved.'