Maples said there will "probably be some arrests that will be made" in connection with the incident, in which a group of male and female students allegedly threw rocks at the teacher and pushed her to the ground.
Maples said a fight had occurred at the school earlier that day and the teacher had been assigned to keep students out of a particular classroom.
When the teacher denied access to a group of students, they allegedly threw rocks at her, and as a larger group gathered, the teacher was pushed to the ground, Maples said.
A vice principal at the school witnessed the incident and came to the teacher's aid. The teacher eventually escaped from the students, Maples said.
School district spokesman Marin Trujillo said the teacher has been placed on administrative leave while police and the school district investigate the incident.
Portola Middle School held a community meeting Tuesday night to talk to parents about safety, with officials from the Police Department and the West Contra Costa Unified School District present to answer questions, Maples said.
The school district agreed Tuesday to provide a school resource officer at the campus, and the officer was introduced to parents at Tuesday's meeting, Maples said.
He said El Cerrito police have had problems in the past with the administration of /*Portola Middle School*/.
"The principal and vice principal have shown a pattern of unwillingness to report criminal activity on the campus, and thought it was more appropriate to handle it with disciplinary actions at the school," Maples said.
Trujillo said, "I am not aware of those concerns, and don't know if the Police Department has communicated that directly to (the school district), but if they have concerns, we really would appreciate if they communicate that to us."
There have been rumors that there is cell phone video footage of the incident, according to Maples, who encouraged anyone with information to contact El Cerrito police at (510) 215-4400.