A white man driven by racial hatred shot dead three Black people in a Florida discount store Saturday before taking his own life after a standoff with police, authorities said.

"He targeted a certain group of people and that's Black people. That's what he said he wanted to kill. And that's very clear," Jacksonville Sheriff TK Waters told a news conference about the gunman, who was in his early 20s.

According to the sheriff's office, the shooter, who has not yet been identified, entered a Dollar General store wearing a tactical vest, armed with an AR-style rifle and a handgun.