LOS ANGELES, Feb. 21 (Xinhua) -- Los Angeles County sheriff's officials said Wednesday that deputies last Friday thwarted a student's plot to open fire at El Camino High School in Whittier, 30 kilometers east of the Los Angeles downtown, just two days after the fatal mass shooting occurred in Florida.

At a press conference held in headquarter of Los Angeles County Sheriffs Department (LASD), a large amount of weapons and ammunition that confiscated from home of the suspect were showed, including two AR-15 style assault rifles, two handguns and magazines able to hold more than 1,200 bullets.

Two brothers were in custody in this case, one is 28 years old and another is a student of El Camino High School, Sheriff Jim McDonnell said at the press conference. He did not disclosed name of the 17-year-old student since he is still a minor, but saying he was arrested on suspicion of making criminal threats.

McDonnell said the student's brother, an Army veteran Daniel Eriberto Barcenas, claimed ownership of the weapons, but the the weapons "were readily available" to the student.

Barcenas faced multiple charges, including possession of an assault weapon, import of a high-capacity magazine, failure to register a handgun and criminal storage of firearms, the sheriff said.

Marino Chavez, Security Officer of Norwalk La Mirada Unified School District, told reporters at the press conference that the student last Friday was upset by a request from a teacher to take off his headphone in class otherwise he would be prohibited to go to school next day then he made comment outside the classroom, threatening to open fire at campus.

According to the principle of the school, students cannot possess electronic devices while class is in sessions.

Chavez said the student at first threatened that he would carry out the shooting in three weeks but told him later that he was just saying that without "real meaning."

However, Chavez, who overheard the students' comments at that time, called deputy and an investigation resulted in finding a collection of weapons and ballistic evidence at the student's home.

This case happened just two days after a mass shooting at Marjory Stoneman Douglas High Schoo in Parkland of Florida, where 19-year-old former student Nikolas Cruz killed 17 people with a rifle that he purchased legally.

Both McDonnell and Elaine Williams, School Safety Chief of the Unified School District, praised Chavez' s response at the press conference, saying the cooperation between "attentive" school guards, community and police is important to keep the campus safety.

The Norwalk La Mirada Unified School District released a "Safety Message" on its official website Tuesday, in which the case was not mentioned.

But it said "We regularly review our Emergency plans for each site that includes responses to natural disasters, but also for intruders and threats on campus. In addition, we conduct safety drills regularly and collaborate with local law enforcement to ensure our school sites are secure."

"We want to encourage you and your children to report any observed suspicious behavior to law enforcement or school officials, as appropriate. As the saying goes - if you see something, say something. This will allow a prompt and appropriate response." the message read.