The girl was stabbed by an intruder at Stagg High School, Stockton Unified School District officials said.
A school officer was on site and quickly took the suspect into custody. “He didn’t put up a fight when he was arrested,” district spokesperson Melinda Meza said.
Online jail records show Gray is being held without bail and is scheduled to appear in court Wednesday afternoon.
CNN was not immediately able to determine if Gray has an attorney.
“My daughter didn’t have any enemies … she was a good kid, a great kid … I just feel like it’s a dream. We’re just trying to wake up,” Manuel Reynaga, Alicia’s father, told KCRA at a vigil for his daughter Monday night.
A team of counselors was sent to Stagg High School and other schools in the district to support students and staff, officials said.
Detectives are investigating the attack and are working to determine a motive and whether there was any relationship with the victim, according to SPD Deputy Chief Eric Kane.
“This is still an active investigation and we will release more information as it becomes available,” the SPD post said.