Three Petaluma City Schools campuses went into lockdown for 20 minutes on Wednesday, September 16, 2026, after students alerted staff that a classmate had brought a gun onto the Casa Grande High School campus. Police detained the female student, recovered the firearm from her backpack, and confirmed no one was injured.
The lockdown began at 11:15 a.m. and was lifted by 11:35 a.m., according to KRON4, which reported that Casa Grande High School, Sonoma Mountain High School and the Petaluma Transition Program were all affected. The Petaluma Police Department responded immediately and worked with school staff to identify and locate the student, and officers ultimately removed her from campus. Investigators found the gun was not loaded, and police reported there was no further threat to students or staff.
It was students themselves who set the response in motion. According to Patch, students reported the potential firearm to staff, which triggered administrators to execute safety protocols before notifying police. Petaluma City Schools Superintendent Davina Goldwasser commended the students for reporting the safety concern immediately, though she declined to share additional information about the case, citing student privacy concerns.
Charges and an Active Investigation
The student was charged with minor in possession of a firearm and possession of a firearm on school grounds, and she was booked into juvenile hall, per the KRON4 report. The investigation remains active, police said. Under California Penal Code § 626.9, the Gun-Free School Zone Act of 1995, possession of a firearm on school grounds is punishable by two, three, or five years in state prison, while possession within 1,000 feet can carry a county-jail misdemeanor or a felony depending on specified circumstances; the statute also contains exceptions, according to Justia Law. That statute applies to every public and private K-12 campus statewide.
District officials said school operations returned to normal after the lockdown lifted, and students are safe. The district acknowledged that situations like this can be stressful for students and families, and it encouraged anyone needing support to speak with a trusted adult on campus, noting that counseling and mental health staff remain available.
A Pattern of Security Scares at Casa Grande
Wednesday's incident is not the first weapon-related scare near Casa Grande this year. In March, Petaluma police arrested a 16-year-old boy near the campus after he pointed what appeared to be a firearm during a fight on the 3000 block of Cross Creek Drive; officers used a drone and K-9 unit to track down a discarded backpack containing two replica handguns and a live .45-caliber magazine, as reported by Bay City News. The suspect had fled toward a creek bed near Casa Grande Road before officers caught up with him.
The campus has also weathered other security controversies in recent years. In September 2024, a 14-year-old Petaluma resident was arrested and booked into Sonoma County Juvenile Hall after posting social media threats targeting both Casa Grande and Petaluma High School, according to CBS News; police confirmed no weapons were found at the suspect's residence. And in February 2023, two masked students stormed a Casa Grande classroom in an attack that drew criticism over delayed notification and lockdown procedures; a safety roundtable followed, along with calls for training, CBS News also reported.
Petaluma City Schools has since leaned on the STOPit app, a third-party anonymous reporting tool that lets students, parents and community members send real-time safety alerts directly to school authorities and emergency dispatchers. The app was previously used to flag threat posts aimed at Petaluma's secondary campuses, per the same CBS News account. Hoodline also covered a written threat found in a Petaluma High School bathroom in October 2023, which triggered a joint investigation between police and district administrators.
Regional Context and Support Resources
The lockdown also comes amid a broader rise in youth firearm cases across Sonoma County. In neighboring Santa Rosa, juvenile firearm possession arrests jumped from four in 2022 to 21 in 2023, according to the City of Santa Rosa, with gang violence cited as a factor. Earlier this month, the Sonoma County Office of Education announced free bilingual youth mental health workshops across the county to support students and families dealing with behavioral and emotional challenges, according to KSRO.
Despite the string of security incidents, Casa Grande earned its first-ever California Distinguished School designation in March 2026 from the California Department of Education, based on 2025 metrics covering academic achievement, school culture and low chronic absenteeism. The school was one of only three secondary schools in Sonoma County recognized during that award cycle, according to information from Casa Grande High School. How the student obtained the firearm has not been disclosed, and it remains unclear whether additional charges will follow as the investigation continues.
