OAKLAND — An 18-year-old Vallejo man was shot in an altercation early Saturday morning in Oakland’s Uptown, authorities said.

He was in stable condition at a hospital and was being treated for a gunshot wound to his lower back, according to authorities.

The shooting happened around 2:21 a.m. Saturday in the 500 block of 17th Street.

According to initial police reports, there was a physical altercation involving the Vallejo man and another man, when a third male shot and wounded the victim in the lower back.

The shooters’ escape was aided by a fourth man, who punched an Oakland police officer trying to chase after the suspect, authorities said. That man was arrested for battery on a police officer, according to the report.

Police are investigating what started the fight that led to the shooting. Anyone with information can call investigators at 510-238-3426.

Staff writer Harry Harris contributed to this report.