A Florida Uber driver shot and killed a man who was chasing his car with a pickup truck and threatened him, authorities said Wednesday.

Jason Boek, 34, was fatally shot at around 2:20 a.m. Tuesday morning after leaving a bar in Dundee, Florida, and chasing Uber driver Robert Westlake, 38, in his pickup truck, Polk County Sheriff Grady Judd said at a news conference Wednesday.

Boek apparently saw his girlfriend and a bartender help another woman into an Uber and mistakenly thought his girlfriend had gotten into the car, Judd said.

Boek became enraged and sent his girlfriend, who was still at the bar, a series of text messages, Judd said.

"The boyfriend is explosive. He's stalking his girlfriend, he's angry with her and he tells her 'I'm going to F up the Uber driver'" Judd said.

Jason Boek Polk County Sheriff's Office

In dash cam video released by the sheriff's office, Boek can be seen cutting off Westlake's car before stopping in the middle of the road and getting out, walking towards the vehicle.

"I say something?" Westlake asks.

"You know I got a pistol?" Boek responds, approaching Westlake's car while holding his cell phone like a gun. "You want me to f---ing shoot you?"

A gunshot is then heard and Westlake and the passenger separately exclaim "Oh my God!"

In a 911 call, Westlake can be heard saying Boek "ran me off the road, jumped out of his vehicle, I couldn't get away."

Westlake shot Boek once in the chest, police said.

"He came towards me, shouting he's got a pistol reached toward his waistband," Westlake says on a 911 call made public by the sheriff. "I fired one shot from my pistol. He dropped his cell phone I kicked it away, I didn't realize it was a cell phone at first."

"I'm applying pressure to the wound, he's faintly breathing," he added.

The sheriff's office said Westlake has a license to carry a firearm, works in security and had just finished the police academy. Neither Boek's girlfriend, the woman who got into the Uber nor Westlake knew each other, Judd said.

"At the end of the day the message is clear, don't mess with the Uber driver. Leave the Uber driver alone because he just might be a certified police officer in waiting," Judd said.

"This is a justifiable homicide all day long. You have the right to protect yourself," he said, adding,"This is a classic 'stand your ground' case."

Floridians are allowed under the "stand your ground" statute — which was first enacted in 2005 and backed by gun lobbyists — to defend themselves with deadly force if they believe they are in imminent danger or death. The person being threatened is not required to try and flee the scene.

A spokesperson for Uber said in statement, "We are saddened by this unfortunate incident and will continue to work with police on their investigation."

Boek's family spoke to NBC News Wednesday from their home, where they said that they were distraught and that he was a loving father who was beloved by many but made a bad choice. They also insisted the Uber driver had time to leave the scene instead of shooting.

"He's not a bad person. He needed help," mother Michele Boek, said.

"How he was portrayed in that press conference is not who he is as a person," said Jenna Irby, Boek's sister. "Now my 2-year-old son is never going to know him," she added through tears.