ST PETERSBURG, Fla. -- A man is in serious condition after he got into a fight with his Uber driver.

St. Petersburg Police say around 7:30 p.m. Thursday, the Uber driver picked up a paying passenger. The two got into an argument over the route the driver was taking.

The driver pulled over to a convenience store when they got into a physical fight. It was unclear who started the fight, officials said.

The driver punched the passenger, knocking him unconscious.

A witness said he didn't know what was going on.

"I walked up and saw this guy laying on the ground and this woman was pressing on his chest trying to bring him back," said Carlton Reid. "He was unresponsive. That's when the paramedics came up and tried to ... do something too."

The passenger is hospitalized with serious brain trauma. His injuries are considered life-threatening.

Investigators are speaking with witnesses and the driver is cooperating. Although he has not been charged at this time, this is still an ongoing investigation.

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