He approached the student, questioned him and brought him to the office.The student confirmed what he said, but said he was only kidding, Chavez said.
The 17-year-old student from the second incident, is in custody, McDonnell said.
Since the Florida school shooting on February 14, there have been 19 school-related threats in L.A. County that have been reported to the department's Criminal Intelligence Bureau, according to McDonnell. Detectives obtained a search warrant for the residence, where they allegedly discovered two AR-15 rifles, 90 ammunition magazines and two handguns, the sheriff said, adding that one of the assault rifles was unregistered.
Local law enforcement officials said they've seen a surge in tips about potential school shootings in 2018.
In the El Camino case, McDonnell said a security guard overheard the student say he was going to shoot up the school sometime in the next three weeks and that a semi-automatic weapon was registered to the student's home address. Threats are prosecuted "fully, whether the suspect has the means to carry out the threat or not".
The alleged threat was overheard by a school security officer at El Camino High School, located in Whittier, California.
He said the safety of students and staff is the highest priority.
Redlands police put extra resources, including high-visibility patrols, at a school campus any time a credible threat is identified, city spokesman Carl Baker said.
But it's clear that the threats on social media and in conversations are getting more attention from the public, especially students, some who seem more willing to report concerns despite the possibility of unfairly being labeled a snitch.
The student was arrested on charges of making criminal threats. The other wasn't registered, a felony in California. Barcenas was booked into the Norwalk sheriff's station and held in lieu of $35,000. Calls to the Department of Defense seeking comment about Barcenas' service record were not immediately returned.
Chavez said the teen wasn't allowed to go to his fifth period class on Friday because of the discovery of the headphones earlier. "And this student wasn't happy about that...."
"I believe that we have been at a heightened state of awareness for quite some time", Madden said. The 15-year-old boy said the message was a joke.
McDonnell said that it was not clear how serious the Whittier student was about committing violence, but after the attack in Florida investigators' "main interest was to avoid letting anything like that happen".
There has been criticism of the Federal Bureau of Investigation for their failure to pass on concerns about Cruz to local officers before the Florida shooting.
"In Northern California, police said they recovered a firearm from the home of an 11-year-old boy who had barricaded himself in a Santa Cruz classroom Tuesday and planned to harm specific students". They also said he had ammunition and loaded magazines in his room.
Other authorities, including the two arresting deputies, school district officials and the security officer are also slated to be there.