The incident happened Monday night at the hibachi restaurant on Hawthorne Boulevard, according to the Torrance Police Department.
Police say it started when a manager and an employee were involved in an altercation. Things escalated when the manager asked the employee to leave, which he allegedly refused to do.
A security guard intervened and tried to help the manager escort the employee out. That's when a physical fight broke out.
Footage shows stunned diners moving out of the way and grabbing their belongings to leave amid the commotion.
The security guard suffered injuries to their face and head and was treated at the scene. The employee left before officers arrived at the restaurant, police added.
Anyone with information is asked to contact Torrance police at (310) 328-3456.