LEMON GROVE, Calif. (FOX 5/KUSI) -- Authorities in East County are investigating after a student at Lemon Grove Academy Middle School reportedly brought a replica firearm to school last week. According to a statement released Tuesday by the San Diego County Sheriff's Office, other students observed the 14-year-old suspect with a firearm in his backpack on Friday, Dec. 13 before 2 p.m. School staff did not learn of the incident until Monday, SDSO said. Once they were notified, school administrators immediately contacted the Lemon Grove Sheriff's Substation. At-risk woman last seen walking in Mount Soledad missing Detectives contacted the student and his parents and learned the firearm was a plastic BB gun, SDSO said. The BB gun was seized without incident, according to the department. After investigating, deputies determined there were no known threats to students at Lemon Grove Academy Middle School. The student's identity is not being released due to him being a minor. However, SDSO said the investigation into the incident is ongoing. SDSO wants to remind students that if they hear any threats or even potential violence, they should approach school staff or call the anonymous Student Speaking Out hotline at (888) 580-8477.