The attack took place Wednesday and the names of neither the student nor the teacher were released by the Long Beach Unified School District.
A spokeswoman for the Long Beach Unified School District, Elvia Cano, would not say what may have precipitated the attack, but the assault was being investigated by the district. She also said the student was not arrested.
The investigation could lead to a suspension or expulsion of the student, officials said.
The melee was broken up by other students in the class, according to Millikan High School's principal, Alejandro Vega, who thanked the students for intervening.
Vega also sent out an email to the parents of students at Millikan in which he generally explained the situation but did not reveal the names of the involved parties, citing confidentiality restrictions.
Vega then sent out a follow-up message to Millikan families on Thursday.
"Some of you have reached out with questions regarding yesterday's incident and communication," he wrote to parents. "A student physically assaulted a staff member while in class, where students intervened to stop the situation. I cannot provide further specifics due to confidentiality laws, however, this incident is an opportunity to remind your child that assaulting anyone at school or acting inappropriately is never acceptable and will result in disciplinary actions. Your continued partnership in fostering kindness and mutual respect for others is critical to ensure our school community is safe. As a reminder, our Wellness Center has various resources available for students who are in need of support."