The FBI is not aware of any motive or ideology that drove a 16-year-old boy to shoot and kill two teenage schoolmates and injure several others on his birthday.
A 14-year-old boy and a 16-year-old girl arrived in critical condition at a nearby hospital but later died.
The suspect is in "grave condition" after surviving a gunshot wound to the head, according to the Los Angeles County Sheriff’s Department.
Police say today is his birthday.
Three other people are being treated for injuries at area hospitals.
As dramatic aerial footage showed students being escorted from campus by armed deputies, politicians and gun control advocates railed against conditions they argue paved the way for yet another deadly school shooting.
News of the shooting was breaking as Senator Chris Murphy was introducing a measure calling for universal background checks, a proposal that was shut down by GOP senators.
"Republicans objected, my motion failed, and now, as a consequence, the slaughter of our children will continue," he said. "Devastating."
California Senator Kamala Harris told MSNBC that it's "pathetic that people yield to a gun lobby on an issue that affects all our children."
Katie Hill, the former California Congresswoman who recently stepped down from office, said in the statement that the "time is now" to defeat gun control opponents.
Follow updates as they happened.