Southern California authorities have said that a school shooting plot was foiled, AP reports. Just days after a gunman took 17 lives at Marjory Stoneman Douglas High School in Parkland, Florida, a security officer at El Camino High School overheard a student threaten to wage a similar attack. Allegedly, the student said “he was going to shoot up the school sometime in the next three weeks.”

Police arrested the 17-year-old student on suspicion of making criminal threats. His older brother, a 28-year-old Army veteran, was also arrested on five weapons charges. Police found hands guns, two assault rifles, and 90 high-capacity magazines in the elder brother’s home. One of the assault rifles was not registered, which is a felony in California. The student is said to have an extensive disciplinary history. Marino Chavez, the school security officer who heard the threat, says he questioned the teen afterwards. Chavez says the teen admitted he made the threat because a teacher told him he couldn't wear headphones in the classroom. Chavez said the threat was a joke.

The school wasted no time in reporting the incident. Robert Jacobsen, general counsel for the Norwalk-La Mirada Unified School District, said “They felt there was enough there that they should call law enforcement so they can investigate further.” Jacobsen added, “In this day and age, we have to be proactive and make that report and go from there." Superintendent Hasmik Danielian said in a statement that “we responded quickly and effectively” as soon as they learned of the threat.