A shooter killed four people and wounded 10 others on Sunday at a video game tournament that was being streamed online from a restaurant in Jacksonville, Florida, local media said citing police sources.
The Jacksonville Sheriff's Office said a suspect was dead at the scene. "Searches are being conducted," it said on Twitter.
Emergency crews and law enforcement flooded into The Jacksonville Landing, a waterfront dining, entertainment and shopping site in the city's downtown.
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.
It was livestreaming the tournament when several shots rang out, according to video of the stream shared on social media. In the video, players can be seen reacting to the gunfire and cries can be heard before the footage cuts off.
One Twitter user, Drini Gjoka, said he was in the tournament and was shot in the thumb.
"Worst day of my life," Gjoka wrote on Twitter. "I will never take anything for granted ever again. Life can be cut short in a second."
The Florida shooting occurs amid a debate about 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.
The sheriff's office said many people were transported to hospital, and its deputies were finding many people hiding in locked areas at The Landing.
"We ask you to stay calm, stay where you are hiding. SWAT is doing a methodical search," it said on Twitter. "We will get to you. Please don't come running out."
Florida Governor Rick Scott said he had offered the Jacksonville Sheriff's Office any state resources it needed.
Reacting to news of the shooting during the tournament involving its video game, Madden 19 maker Electronic Arts Inc said it was working with authorities to gather facts.
"This is a horrible situation, and our deepest sympathies go out to all involved," the company said on Twitter.