"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 gun was not loaded, but there was ammunition by the gun," Miyashiro said.
The student told an adult, and the third grade classroom was cleared out immediately.
Police arrived within minutes and found the gun, alleging that the handgun belonged to a 51-year-old female teacher. Jayne DeArmond was arrested and faces serious charges.
"We have a zero tolerance. Not only can students not bring weapons to class, but obviously adults can't either. There's also California Penal Code that basically makes it a felony to bring a firearm onto a school ground. She was arrested for the felony as well as for child endangerment," Miyashiro said.
Letters were sent to parents about the incident, and officials said counselors are on campus at Diamond Elementary School for anyone who needs to talk about the incident.
No one was injured in this incident. Police are unsure why DeArmond brought the gun to school or how long it had been there.
Many parents say the fact the gun was not loaded does not matter and wondered why a teacher allegedly brought it to school. Parents and police were grateful that the student who made the discovery remembered what to do.
The teacher was released from jail after posting $20,000 bail. Police said she is not working at the school at this time.