Last December, when a student at Bolinas-Stinson School made a threat in class to shoot up the school, superintendent John Carroll said he knew “the kid personally and I dealt with it. Kids say unwise things sometime.” He contacted the Marin County Sheriff’s Office and deputies interviewed the student. “It’s a demonstration of how seriously we take this,” Mr. Carroll said. “We went through the protocol: searched him, interviewed the parents and searched the house for weapons.”

He also sent out an email to the school community to counteract “false rumors” he said were spreading. In the letter, he characterized the indecent as “a moment of verbal carelessness” and didn’t detail what the student said or explain law enforcement’s response. He did urge parents to talk with their kids about how jokes about violence aren’t funny or appropriate. Mr. Carroll said he hasn’t received any responses from parents about the incident.  

Local schools have been taking proper measures to prepare themselves for the worst-case scenario of an active shooter on campus amid a surge in shootings across the country. California was listed as a state of “moderate” concern by the Educator’s School Safety Network, a nonprofit that has composited threats and incidents of violence across the country, but there are no reports of serious threats or incidents of violence at Marin County schools. The Marin County Office of Education does not keep a database of threats.

Josie Sanguinetti, the school resource officer for the sheriff’s office, said schools in West Marin have been very communicative, and that parents and students often reach out on social media. 

The sheriff’s office hosted a training for school administrators last November, when representatives from each West Marin school were instructed on the Department of Homeland Security’s protocol: run, hide or fight. 

Local schools are conducting lockdown drills—which are not required under California’s education code, but are considered best practices—with varying frequency. Principals have established relationships with Officer Sanguinetti, and some campuses have adopted new practices for alerting people of a threat or danger. 

“Every school has their own comprehensive training program, and there should be one, if not two or three, lockdown drills for each school per year,” Mike Grant, the county office of education’s director of maintenance and operations, said. 

Nicasio School practices four lockdown drills each year, two planned and two surprise drills, and Lagunitas School conducts monthly drills. Tomales High School averages one per semester, while the Bolinas-Stinson Union and West Marin Schools complete one drill a year. (Schools are required by the state education code to practice drills for earthquakes and fires several times throughout the year.)

The purpose of the drills is not just to prepare students, but also the adults on campus. Besides quickly locking the door, teachers are advised to pull down shades or draw curtains and create a blockade at the door. In the event that adults must fight back against a shooter, they’re advised to throw whatever they have their disposal, such as a chair or a fire extinguisher.

“We can’t forget what happened in Tehama County, in a small community like ours,” Barbara Snekkevik, the Nicasio School principal, said in reference to the Rancho Tehama Reserve shooting last November, when a gunman opened fire on an elementary school, injuring several students. “Those teachers saved every one of their kids’ lives because they knew what to do.”

Some West Marin schools use different language to talk about dangers depending on the age group. During drills, Ms. Snekkevik said teachers may tell their kindergartens and early elementary schoolers that a wild animal is roaming campus. But by the time a student reaches middle school, there’s no pampering the message. 

“Our middle schoolers are on social media and understand the reality of the threat today,” she said. “While we don’t try to sensationalize or scare anybody, we definitely try to be as real as we can in an age-appropriate way.”

Bob Raines, superintendent for Shoreline Unified School District, said someone at his schools “just hollers ‘Lockdown!’ and everybody understands what to do.”

Jason Richardson, principal for Bolinas-Stinson School, pointed out that drills can sometimes come with unintended consequences. “Lockdown drills can freak people out,” he said. “Parents sometime feel we’re creating situations that are scary for kids, but we feel it’s a necessity.” 

Since lockdown protocol requires covering windows, West Marin and Inverness Schools—which have walls of large windows—invested in new curtains and window coverings two years ago. Principal Matthew Nagle said they spent about $15,000 on coverings and installed new locks on their doors (called “Columbine locks”) that allow classrooms to be locked from the inside. 

At Bolinas-Stinson School, the board recently approved the use of a mobile app called Kaymbu, which can connect each teacher to the internet to send alerts from the classroom. 

Laura Shain, principal at the Lagunitas School District, said she can sidestep her campus’s lack of a P.A. system by converting every phone in the classrooms to a speaker. She calls all phones simultaneously from her office to grab attention, beginning by blowing a whistle to signal an alert.

Officer Sanguinetti visits schools during lockdown drills to build working relationships that Mr. Grant says are imperative. “You’re working in conjunction with their response,” he said. “It is run, hide, fight, but the key is that you’re getting input and direction from local first responders. Seconds matter—that’s the thing that law enforcement and first responders say.”

If a 911 call went out from Tomales Elementary or High School, the response could come from various agencies, including the Sonoma County Sheriff’s Office, California Highway Patrol and even the Coast Guard, which has a station just six miles away.

“I’m looking into partnering with the Coast Guard,” Adam Jennings, principal for Tomales High, said. “They’re not roaming vast countryside like the C.H.P. and sheriff.”

Schools also have systems in place to respond to a student who exhibits behavioral warning signs. If a concern arises about a student’s mental health, Nicasio and Shoreline schools have a so-called student study team—comprised of the principal, the school psychologist, a counselor, teachers and a resource specialist—to discuss next steps.

Ms. Shain said her district is keeping an eye on what their students are scribbling, and has banned drawing violent pictures on campus. “We’re reinforcing the idea of not drawing pictures of guns and mass destruction,” she said. “We want to just make it really clear that it’s not okay at school. If everybody adheres to that, it becomes easy and a norm.”

Mary Jane Burke, Marin County’s superintendent of schools, agrees that the focus should be on early intervention. “Everything that we know about supporting our kids and teachers in school is involved around appropriate intervention,” she said. “To make a determination that we are going to essentially put a moat around our schools is not the answer. We should deal with issues at the time we need to and not resort to using firearms.” (President Trump has advocated arming teachers and school staff with concealed firearms following the recent massacre in Parkland, Fla.)

West Marin schools have had a couple of concerning instances in recent years—a suspicious individual walked through Tomales High School’s campus a few years ago and Lagunitas School was once put on lockdown after a vehicle was stolen in Woodacre—and administrators know that preparedness is key. 

“We have to make sure we don’t lull ourselves into a false sense of security,” Mr. Nagle said. “We get a lot of strangers on Highway 1. We’re not immune—we know that—and that’s why we practice the drills.”