Two dead, multiple others shot after gunman opens fire at Jacksonville gaming tournament (UPDATED)

A gunman opened fire at a gaming tournament at the Jacksonville Landing in Jacksonville, Florida, Sunday afternoon. The Jacksonville Sheriff's Office initially described the event as a "mass shooting.

What are the details?

Jacksonville Sheriff Mike Williams said at a press conference Sunday evening that two people were fatally shot in the incident while nine others sustained gunshot wounds, according to CNN. An additional two people were injured fleeing the scene.

Williams identified the deceased as Elijah Clayton and Taylor Robertson. He further told reporters the suspect, a 24-year-old from Baltimore who was in Jacksonville for the gaming competition, killed himself.

Authorities said the killer used a semiautomatic handgun in the attack. Federal authorities were in Baltimore searching his residence Sunday evening.

The gunman opened fire during a Madden Football gaming tournament at the Chicago Pizza restaurant in Jacksonville Landing, an open area on the St Johns river with many shops and restaurants. Police responded to reports of gunfire at 1:34 p.m. Williams said the first officers arrived on scene within two minutes of the initial 911 calls, according to WJXT-TV.

The killer's motive is not yet clear, nor did Williams reveal any possible reasons for the attack. The Los Angeles Times reported earlier Sunday, citing another competitor at the tournament, that the gunman opened fire after he lost a game in the competition. The source said the gunman "targeted" several people before turning the gun on himself.

A video posted to social media, which quickly went viral, appeared to show a livestream of the tournament when shots rang out. Gunshots and screams are audible in the clip, however it does not show the shooting itself.

This story has been updated.