Police in Jacksonville, Florida, reported "multiple fatalities at the scene, many transported" at Jacksonville Landing, a downtown marketplace hosting a video game tournament on Sunday. They added that one suspect was dead at the scene as they continued to search.

Local authorities warned residents to stay away from the area due to a mass shooting and said it was unclear whether there was a second suspect.

Law enforcement officials told local NBC News affiliate First Coast News that four people are dead and 11 are injured.

"Stay far away from the area," the Jacksonville Sheriff's Office tweeted. "The area is not safe at this time."

The Jacksonville Sheriff's Office confirmed to NBC News that they sent multiple officers to respond to a shooting downtown.

"We can’t stress enough to stay away. Many blocks away," the sheriff's department said in a second tweet.

People were in the Jacksonville Landing area prior to the shooting, and police said they understood many were hiding in locked areas after the shooting was reported. Authorities warned that those people should remain where they are and avoid running out while the SWAT team conducted its "methodical search inside The Landing."

The Bureau of Alcohol, Tobacco, Firearms and Explosives said on Twitter that it was also "responding to a reported mass shooting in downtown Jacksonville."

The county sheriff, Mike Williams, and Jacksonville's mayor, Lenny Curry, were expected to address members of media later in the day on Sunday. The city said the two were in contact regarding the reported mass shooting.

The shooting appears to have occurred inside a pizza restaurant that includes a bar dedicated to video games and other forms of gaming. The bar was in the middle of hosting the Madden 19 Southeastern Qualifier Tournament, which comes with a $5,000 prize. Madden 19 is the latest NFL football video game put out by sports game publisher EA Sports.

On a video of a live stream shared online, individuals playing in the Madden NFL video game tournament are interrupted by a series of popping blasts and screaming.

"What's he shooting with?" one person can be heard asking in the live-stream audio.

NBC News has not confirmed the authenticity of the video.

An EA Sports spokesman said that they were aware of "an incident at a sanctioned Madden Championship Series competition in Jacksonville" and said they were working with authorities to gather additional information.

The spokesperson said it was "a horrible situation, and our deepest sympathies go out to all involved."

Florida Gov. Rick Scott, a Republican, said he had spoken to Jacksonville Sheriff Williams and offered any state resources he might need via the Florida Department of Law Enforcement.