CHARLOTTE, N.C. -- A mother and three teenagers were charged after a disturbance at a Charlotte middle school Friday morning.

The mom was identified by police as Olga Cortez.

Cortez says her 13-year-old son is being bullied so she drove to Coulwood Middle School in northwest Charlotte to confront the bullies, according to police.

Cortez identified the students she believed to be bullies to school staff. During that time, police say Cortez became verbally irate. A teen who she identified physically assaulted Cortez. The mom pulled a knife and waved it in the air after two 13-year-olds who she identified as the bullies.

CMS staff got the mother under control and she put the knife back in her vehicle before a School Resources Officer arrived. No one was hurt.

Coulwood Middle School went into "self-contained mode due" during the incident. The principal sent the following message to parents: "Before school started, we went into self-contained mode due to police activity in the bus parking lot. CMPD responded and arrested a suspect. No students or staff were injured."

Police charged all three teenagers with public affray and two of the teens were additionally charged with simple assault for assaulting Cortez.

Cortez has been charged with three counts of assault with a deadly weapon and one count of weapon on school grounds.

Cortez got out of jail Friday night. Her son was suspended from school.