HESPERIA, Calif. (KABC) --A student at Encore High School in Hesperia has been arrested after authorities found what they called a detailed plan to shoot 33 students and staff members of the campus, officials said.
San Bernardino Sheriff John McMahon said the student had a detailed plan and a list of 33 names "as potentials that could have been shot at the school."
He said the student, who was not identified, also had "limited access to firearms."
The student had also discussed explosives in the plan, but a bomb squad and K9s that searched the school found no evidence of any explosive devices.
"There certainly was the potential in this case for harm," McMahon said. "He had the intent and capability based on what we know today to carry out an attack at the school."
The investigation began Saturday after a parent notified the sheriff's department of threats that were posted on social media.
Investigators spoke to the student on Sunday, but did not have enough at that point to warrant an arrest, McMahon said.
After speaking to students and staff members on Monday, a search warrant was obtained for the two homes of the student's parents and enough evidence was found to merit an arrest. The evidence included the list and a detailed plan.
"That plot was very well-detailed and he was very set on doing something at Encore High School," McMahon said.
The student was arrested and is being held at a juvenile detention center.
McMahon said officials believe he was acting alone.
After the threats were discovered, but prior to his arrest, the student was not allowed on the charter-school campus this week and "he will not be returning to campus," according to Denise Griffin, CEO of Encore Education Corp.
At the press conference, some distraught parents asked Griffin why the school had not been closed on Monday and Tuesday as the threats were being investigated.
She said the school was first notified of potential threats on social media on Sunday, but at that point the information was not very clear.
Griffin emphasized that safety is very important to Encore and noted her own child attends the school and she felt confident enough in the school's safety to not keep him away from the campus this week.
She said the school has a ratio of about one adult for every 10 kids on campus.
"Encore is our family," she said. "It is very important to us to make sure that our kids at Encore are very well taken care of."