Video shows a confrontation between the teenagers and the sheriff's investigator, who was off-duty at the time.
The investigator is seen in the video wearing a white hat and appeared to have pulled a small handgun after a teen raised his skateboard in the air.
The confrontation allegedly started over loud music and then escalated.
The Orange County Sheriff's Department said in a statement that read in part:
"Orange County Sheriff's Department employees are expected to conduct themselves with professionalism on and off-duty. We take this incident seriously and will fully investigate."
One teen's mother told Eyewitness News that the man did not immediately identify himself as a law enforcement officer.
An internal investigation is underway and the investigator has been put on administrative leave, according to the department.