At the school Saturday, yellow police tape was still up where the stabbing took place in front of dozens of students.
Abraham Lopez, 18, has been charged with murder. He remains in jail without bail.
Authorities said Lopez stabbed his ex-girlfriend, Cindi Santana, Friday morning. The 17 year old died of her injuries later that day at St. Francis Medical Center in Lynwood.
Students said Lopez and Santana were broken up and that they had a fight during their lunch hour. The fight quickly became physical. Witnesses said Lopez punched Santana in the face, began choking her and then pulled out a knife.
According to his booking information, Lopez weighs 250 pounds. Students say he easily overpowered Santana.
Student Raymond Gutierrez described the incident as "brutal" and said Lopez obviously had the upper hand and Santana couldn't do anything to protect herself.
Student Deisy Nava told Eyewitness News that she saw blood and saw a friend of Santana's holding her hand on the ground.
"I feel bad for the family and for all the friends. She's gone but never forgotten. I didn't know her, but all my respects are to her. I wish that wouldn't have happened. I wish there was more security in our school," said Nava.
A varsity football player and a female dean tried to subdue Lopez and suffered cuts. School officials said they are both expected to be OK.
The school was on lockdown Friday, and many parents hurried to the campus after receiving text messages from their children about the stabbing.
Grief counselors will be available for both students and staff Monday. The counselors are also being made available for Santana's family.
Lopez is set to make his initial court appearance as early as Monday.