CHARLOTTE, N.C. -- A student's call for help to his mom may have gotten him more parental involvement than he bargained for.

Police said Inez Horne, 45, was arrested Wednesday at East Mecklenburg High School after she, two daughters and a family friend stormed a classroom to defend her 15-year-old son, who had called home to say he was afraid another student was planning to attack him.

"The mom decided to show up at school and take matters into her own hands," said Charlotte-Mecklenburg Police Officer Robert Fey.

Horne was charged with misdemeanor trespassing. Daughters Keisha Horne, 19, and Marquitta McNair, 18, were charged with misdemeanor trespassing, simple assault and carrying concealed weapons -- Horne a knife, McNair a boxcutter -- according to arrest records. Antwan Buchanon, 20, a boyfriend to one of the daughters, was also charged with misdemeanor trespassing.

Charlotte-Mecklenburg Police Sgt. Randy Haigler said the incident unfolded Wednesday morning around 10 a.m. after Horne's son called to tell her he was being threatened.

"They arrived on campus, they didn't check into the office, they went directly to the classroom and started to assault a 16-year-old student," Haigler said.

Charlotte-Mecklenburg Schools officials say a resource officer followed the group after they failed to sign themselves in as visitors.

"The fact that this situation slipped through security is something that we're going to have to look at now and analyze," CMS spokesperson Nora Carr said. "That's something we have to address."

Haigler said the resource officer quickly defused the situation and that the weapons carried by McNair and Horne were never drawn.

Police did not release the name of Horne's son, who is a juvenile, but Fey said he was charged with resisting arrest.