Police said a Notre Dame High School student was arrested for making shooting threats at the private Catholic college preparatory school, which has an attendance of about 1,200 students.
The student, only identified as a 16-year-old boy, was arrested Friday after detectives learned of the incident.
"At that point, although there was not a weapon on campus and students were never in any immediate danger, we thought it best to report the matter to police," said Brett Lowart, the school's president.
Police say the student told a friend he was going to kill two students and a teacher at the school. Police served a search warrant on Monday and recovered a working World War II-era M1 rifle that they believe the student was intending to use to carry out the attack. Investigators also took a computer from the teen's home.
The teen was released from jail on Tuesday after the Los Angeles County District Attorney rejected the case citing insufficient evidence. However, the Los Angeles Police Department plans to resubmit the case.
"We resubmitted our request to the DA and we'll see what happens from here," said LAPD Officer Cleon Joseph, who said the threats appear to be credible.
The shock was still fresh for students at the high school on Wednesday.
"He was a nice kid, I mean, he was kind of quiet," said one student.
"I was very surprised especially in this school. It's a Catholic school, and we're taught all the Catholic morals and stuff like that," said another student.
A relative who spoke to Eyewitness News and didn't want to be identified said the teen was repeatedly bullied at the school and acknowledged the boy made a mistake saying something he shouldn't have, but says there was never any real threat behind the words.
The school and police, however, could not take that chance.
"I am thrilled that our students reacted the way we've taught them, if they hear of anything scary to go to an adult," said Stepanie Connelly, the school's principal.
Parents said they were notified of the incident the day it happened and are pleased with the school's reaction, but it still doesn't make the news any easier to hear.
"I'm surprised at anytime you hear about anything like this no matter where it is. Whether it's here, at another school, other state. Those things amaze me," said Lenny, a parent.
The student is no longer at the school, but the school would not elaborate on whether that decision was made by school authorities or by the student and his family.