Here's a timeline of what happened according to an account provided by Los Angeles County Sheriff Alex Villanueva and Capt. Kent Wegener at a news conference on Thursday as well as social media posts from law enforcement:
- It's not clear exactly when the shots first rang out, but officials later said only 16 seconds elapsed from the moment that the suspect pulled a gun from his backpack to when he turned it on himself.
- 7:38 a.m. - The Los Angeles County Sheriff's Department's Santa Clarita Station receives the first 911 call about a shooting at Saugus High School. Several additional calls followed in the minutes to come.
- 7:40 a.m. - The first law enforcement units were on scene at the school within two minutes. In the school's quad area, they encountered multiple gunshot wound victims, including the suspect. As first responders triaged the victims and took them to local hospitals, the school was locked down and partially evacuated.
- 7:56 a.m. - LACSD asks residents to avoid the area. Minutes later, authorities announce that schools in the area are on lockdown.
- 8:17 a.m. - Santa Clarita Valley Sheriff's Station characterizes the incident as an active shooter situation.
- 8:32 a.m. - Authorities warn neighbors near the school to "PLEASE LOCK DOORS and stay inside."
- 8:54 a.m. - The Santa Clarita Valley Sheriff's Station announces that victims had been taken to a local hospital for medical treatment.
- 9:23 a.m. - Female victim dies in the hospital.
- 9:40 a.m. - Villanueva tweets that a suspect has been taken into custody and is being treated at a local hospital. Authorities later identified that suspect as a member of the Saugus student body.
- 11:37 a.m. - Authorities announce in a news conference that a second victim had died.
Click here for full coverage of the Saugus High School shooting in Santa Clarita, California.
The Associated Press contributed to this report.