Breaking : Mass shooting plot for SoCal high school thwarted by alert security guard

Authorities say they've thwarted a student's plot for a mass shooting at a Southern California high school.

The Los Angeles County Sheriff's Department said Tuesday that a security guard at El Camino High School in Whittier overhead a "disgruntled student" threaten to open fire on the school on Friday, just two days after 17 people were gunned down at a Florida high school.

Sheriff's spokeswoman Nicole Nishida tells The Associated Press deputies discovered "multiple guns and ammunition" after searching the student's home.

Officials wouldn't provide additional details but scheduled a news conference for Wednesday.