The Associated Press

JACKSONVILLE, Fla. — A gunman opened fire Sunday during an online video game tournament that was being livestreamed from a Florida mall, killing multiple people and sending many others to hospitals, authorities said.

Jacksonville Sheriff Mike Williams said authorities believe 24-year-old David Katz of Baltimore carried out the attack using at least one handgun at the Jacksonville Landing, a collection of restaurants and shops along the St. Johns River.

He said the man died from a self-inflicted gunshot, adding authorities were still making final confirmation of his identity with the FBI assisting them in Baltimore.

Nine other people were wounded by gunfire and all were in stable condition Sunday evening after going to hospitals, Williams said.

He added that two others were hurt as people sought to flee the gunfire in the panic and chaos that ensued.

Investigators were looking into online video that appeared to capture the scene right before the shooting began, Williams said.

A red dot that appears to be a laser pointer is visible on the chest of a player seconds before the first of a dozen gunshots rings out.

The sheriff’s office used Twitter and Facebook to warn people to stay far away and to ask anyone who was hiding to call 9-1-1.

On Sunday evening, an FBI official in Baltimore confirmed that its agents were searching the family home of the man authorities said they believe was behind the attack. An FBI spokesman, Dave Fitz, said agents had gone to the house of the man’s father in Baltimore.

He declined to release specifics, citing the ongoing investigation.

In Washington, White House spokeswoman Sarah Huckabee Sanders said President Donald Trump had been briefed on the attack and the White House was monitoring the situation.

The Jacksonville Landing, in the heart of the city’s downtown, also hosts concerts and other entertainment.

It was the site of a Donald Trump rally in 2015, early in his campaign for the White House.