Law enforcement officials told TMZ, they were patrolling the Harbor Freeway when they noticed Efron and another man, later identified as his bodyguard, in brawl with three more people.
After breaking up the fight, police questioned the actor, who explained that he and his bodyguard had run out of gas and were waiting for a tow truck. He said the incident began after Efron and his companion threw a bottle out the car's window prompting the transients to confront them.
Efron said he got out of the car after realizing two of the men were attacking his bodyguard. At that point, he got hit in the mouth.
"It was the hardest I've ever been hit in my life," Efron reportedly told authorities.
Sources claim the High School Musical star was intoxicated during Sunday's confrontation. No arrests were made at the scene as police determined it had been "mutual combat."