Alexander has taught the course in the past but Pridgen said he did not know if he had ever brought a live firearm to the school before.
One student suffered an injury to his neck from either bullet fragments or debris falling from the ceiling, Pridgen said.
The parents rushed him to a nearby emergency room for X-rays.
Three California high school students are recovering after being struck by bullet fragments in class.
"It's the craziest thing".
"It's just so insane, I can't believe it", he said. He told KSBW that Alexander had told the class that he wanted to make sure the gun wasn't loaded when it accidentally discharged.
Exactly why the teacher was displaying the weapon at all was not entirely clear.
The teacher has since been placed on administration leave from the school and the Sand City Police Department. The safety of your student is always our top priority, and we will continue to remain vigilant in our efforts to keep them safe while they are under our care'.
Headlines are generating today (March 14) as reports surface about a California teacher accidentally discharging a firearm while in a classroom for public safety and hurting a student.
Alexander's own department will also investigate the matter, Sand City Police Chief Brian Ferrante confirmed in an email to HuffPost.
"I think a lot of questions are on parents' minds are, why a teacher would be pointing a loaded firearm at the ceiling in front of students", Diffenbaugh told KSBW.
He adds that, "Clearly, we will revisit this incident to ensure that something like this would never happen again".
However, Marci McFadden, chief of communication and engagement with the Monterey Peninsula Unified School District, said Monterey school district's policy does make an exception for school resource officers when it comes to carrying guns and other weapons on campus.
Alexander has been a reserve officer with the Sand City Police Department for 11 years.
In addition to teaching, Alexander works as a reserve police officer.
The shooting occurred amid intense national debate over whether to arm teachers across the nation or come up with more sensible gun laws, which allowed the 19-year-old school Florida shooter, Nikolas Cruz, to legally purchase a military-style rifle. President Donald Trump has propagated the idea of arming teachers with guns.