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A curtain blows in an open window of Robb Elementary School in Uvalde, Texas, Monday, May 30, 2022. On May 24, 2022, an 18-year-old entered the school and fatally shot several children and teachers. (AP Photo/Wong Maye-E)

FILE — New Washington, Ohio, Chief of Police Scott Robertson talks with fourth grade students as they huddle in closet a during a lockdown drill at the St. Bernard School in New Washington, Ohio, Jan. 14, 2013. The shooting massacre at a Texas elementary school has spurred renewed calls for school safety, but experts debate whether more heavily fortified schools are the right solution. (AP Photo/Craig Ruttle, File)

Concerned people gather outside of Balboa High School after hearing reports of an active shooter on campus in San Francisco, Calif. on Thursday, Aug. 30, 2018.

On the blacktop of a Montessori school in Oakland, a gym teacher kept his head on a swivel last week, eyeing unfamiliar faces in the parking lot, knowing it’s just him out there to protect 40 children as they play.

A middle school teacher in San Francisco offered to teach staff how to stanch the bleeding from a violent wound.

And at an evening meeting for parents of middle and high schoolers in the city, the discussion turned toward door locks, security cameras and staff communication radios.

The school year began with hope as children filed into classrooms after more than a year of remote classes and pandemic disruptions to their learning and their lives. It is ending with a brutal reminder that schools, like malls, movie theaters and grocery stores, remain just as vulnerable to mass shooting attacks as they were 10 years ago, when the nation was stunned by a lone gunman’s massacre of 26 children and adults in Newtown, Conn.

After a gunman killed 19 children and two teachers in Uvalde, Texas, on May 24, there were — once again — loud and emphatic calls for Congress to pass meaningful gun control measures.

Little happened in 2012, and it already appears little will happen in 2022, after Republican senators blocked a gun control bill in the days following the Texas shooting. In Uvalde, there are also many questions about the police response, and their decision to wait to enter the building as students called 911.

Amid all this, school officials are left with having to figure out the best way to prevent violence and protect children, their teachers and staff. On the same day as the shooting in Texas, a second-grade student in Sacramento allegedly brought a gun and ammunition to school, reinforcing the feeling that the threat is constant and that school violence could erupt anywhere, anytime.

“Enough is enough — how much more do we have to deal with?” said Steve Herrington, superintendent of the Sonoma County Office of Education. “We’re not dealing with the real issue. The gun is the destructive component here.”

School officials across the Bay Area sent out reassurances to parents last week, saying they would beef up security, screen visitors, keep the doors locked. Police vowed to have more uniformed officers patrol around school campuses.

Between the lines of those messages, there is no guarantee. The nightmare of a gunman’s violence could come here. The shared anxiety of parents, teachers and students across the country is not because campuses haven’t adapted to the threat that an armed shooter bent on violence might walk in.

The so-called Columbine locks on many classroom doors that allow children and staff to lock themselves inside were named after the Colorado high school where in 1999 a teacher and 12 students were murdered by two of their peers. They are not yet universal, though many updated and newer schools have them.

By now, many children have participated in active-shooter drills their entire school careers.

Greg Markwith, who oversees San Francisco Unified’s emergency preparedness and crisis response, said schools are required to have robust safety plans and revise them each year. Campuses conduct regular drills for lockdowns, when they need to keep students and staff safe from on-campus perils, and for lockouts, when they need to keep outside dangers from coming in.

“It’s sometimes an uncomfortable topic, but it has to happen, we have to be prepared,” Markwith said.

San Francisco district officials last week announced a new program called the Say Something Anonymous Reporting System, allowing people to report concerns anonymously. Violence prevention is key, Markwith said, and students must feel safe reporting signs of dangerous behavior they might see.

At West Contra Costa County Unified, district officials last week urged principals to ensure there’s just one point of entry to their campuses so visitors can be closely monitored. District spokesperson Ryan Phillips said students have been struggling with behavior issues since schools reopened after pandemic closures, and violent incidents have been on the rise.

“It’s been difficult for students to transition back to being in the classroom — we’re struggling to get back to normal,” Phillips said. “Now especially after the horribly tragic shooting, we know that everyone in the community is thinking about school safety too.”

At James Lick Middle School in San Francisco, Principal Ruby De Tie ditched the remarks she’d written for a ceremony honoring students advancing to high school. Instead, she asked everyone to hug the person next to them — even strangers — and cherish every day.

“It all became very real to me,” De Tie said. “I do feel my school is safe, and we can add more security. But we don’t know ... we just don’t know.”

The tragedy in Texas has led to critiques of the fence that the gunman climbed at Robb Elementary School, the unlocked door he walked through and whether the school resource officer was on-site. In particular, people are asking why law enforcement officers waited for 78 minutes while hiding children trapped in a room with the gunman frantically called 911.

Some school leaders and parents in the Bay Area shared frustration that schools will remain vulnerable as long as guns including deadly assault rifles remain readily available for almost anyone to buy.

“My daughter has had school lockdowns and drills for her entire academic life, which is depressing, but you know you have to do this sort of thing,” said Max Garrone, a parent leader with San Francisco’s middle and high school task force. “The bigger issue is it’s about guns and this country’s relationship with guns.”

“Every other country has figured out how to keep kids safe — gun control works,” said Meredith Dodson, executive director of the San Francisco Parent Coalition. “It’s a failure of our country, failure of our policymakers.”

U.S. Rep. Mike Thompson, D-Napa, who chairs the House Gun Violence Prevention Task Force created after the Sandy Hook massacre in Connecticut, criticized Republican legislators for blocking meaningful and broadly popular gun legislation like background checks. He lambasted his political opponents’ proposals in response to the lives lost in Texas for school grounds security improvements.

“Schools aren’t the only venue for violence,” Thompson said. “I don’t think you can make every place bulletproof. The most expeditious and most effective thing is to expand background checks before anybody could buy a gun.”

The violence in Texas has also stirred public debate about whether the significant money schools have put into security and time into active-shooter drills is effective at keeping children safe.

But drills can be valuable, creating muscle memory people can rely on during an emergency, said Jaclyn Schildkraut, associate professor of criminal justice at State University of New York at Oswego. Schildkraut, who grew up in Parkland, Fla., where a 19-year-old gunman killed 17 people at Marjory Stoneman Douglas High School in 2018, has studied lockdown strategies and drills for the last four years. Locked doors have proved to deter assailants, she said.

Prevention must come before a shooter gets onto campus. Most “leak their intentions in advance,” providing a crucial window for preventing violence if those around them come forward, Schildkraut said.

“At least one person knows,” Schildkraut said.

On a playground at Arbor Montessori in Oakland, physical education teacher Mikael Wooten said goodbye to kids at the end of the school day Friday. Wooten said he felt schools were too locked down and not welcoming enough for the children, but isn’t so sure now. He supports background checks for gun purchases and restrictions on assault rifles — but he’s doubtful politicians in Washington, D.C., will muster the courage to do so.

“They’re our responsibility, from the time they’re dropped off to the time they’re picked up,” Wooten said. “I don’t put too much stock in waiting for change at that level. I have to worry about helping my kids the best way I can.”

Julie Johnson (she/her) is a San Francisco Chronicle staff writer. Email: julie.johnson@sfchronicle.com Twitter: @juliejohnson

Julie Johnson covers the changing climate, sea level rise and strategies to stem California's wildfire crisis. Before joining The Chronicle, she spent 11 years as a staff writer at the Santa Rosa Press Democrat, where she had a leading role on the breaking news team awarded the 2018 Pulitzer for coverage of the 2017 Wine Country fires. Julie has covered murderous pot deals, police corruption and marijuana's rocky path from a black-market trade to a legitimate industry.