Click in the Eyewitness News Story Window above to watch Eileen Frere's report from the scene.
"This gun was kept in a storage area that kids accessed for supplies and things," said Chief Jim Miyashiro of the Santa Ana School District Police.
The student told an adult, and the third grade classroom was cleared out immediately.
The 51-year-old teacher from Costa Mesa was arrested and faces serious charges. District policy and state law ban any type of weapon on school grounds.
Police are unsure why DeArmond brought the gun to school or how long it had been there.
The teacher remains free after posting $20,000 bail earlier this month. The judge ordered DeArmond to stay away from firearms and not to set foot on any school property in Orange County.
"If in fact it was her gun found in the classroom, it was inadvertently brought into class. There was absolutely no sinister intent to do harm," DeArmond's lawyer said in a statement.
"Ms. DeArmond has absolutely no prior record and no history whatsoever for violence. While having the gun at school is dangerous and we regret the incident, there was no motive to do harm -- to anyone at the school or anywhere else."
He went on to say that DeArmond had a nice relationship with her students, the school administration as well as the teachers at the school.
She is expected to be back in court in June.