SAN JOSE, Calif. — Rebecca Wang was just 7 years old the first time it happened.

She remembers vividly her teacher’s panicked face, and her urgent voice telling Rebecca and her classmates to keep quiet, hide behind their desks and stay calm.

They were barricaded in a Los Gatos classroom for four hours until police found the man who’d run across their campus with a gun. Wang didn’t understand what was going on, but when they finally walked outside, her entire family was waiting — and they looked terrified.

“It was pure chaos,” said Wang, now 17. “We didn’t really know what was going on, but we knew the teachers were scared out of their minds.”

After 10 years of waiting for things to change, Wang — a rising senior at San Jose’s Gunderson High — decided to take things into her own hands. This summer, she and three friends will be refining SIREN, an artificial intelligence device they’ve trained to detect gunshots and instantly communicate with all students, staff members and teachers at an affected school, along with the police department.

“It’s sad that we felt like we had to make this device. But as students, this isn’t something we can just choose to ignore,” said Swarnya Srivastava, a rising senior at Monta Vista High School in Cupertino, and member of the SIREN team.

In 2022, there were over 300 school shootings across the country, according to the K-12 School Shooting Database. This year, we’re on track for even more, with 178 school shootings recorded during the first six months alone.

Wang came up with the idea for SIREN after a teenage gunman killed 21 people at Robb Elementary School in Uvalde, Texas, in May of last year. Law enforcement waited for more than an hour outside before confronting the gunman, an 18-year-old who carried an AR-15style rifle onto the campus. In the incident’s wake, the Uvalde community was left grappling with knowing lives might have been saved if police had responded sooner — and they weren’t the only ones.

“Right now, it’s terrifying to be a student in America,” said Wang. “It seems like this nightmare will never stop for us.”

Just months after Uvalde, Wang, Srivastava and two other juniors, Santa Clara High School’s Caitlin Nguyen, and Mission San Jose High School’s Audrey Wang, started brainstorming ways to decrease police response time and increase the information shared with students, teachers, parents and school staff who are under attack. The four had met through hackathons and coding camps, and in the past, had bonded over being women in technology.

Ultimately, they came up with SIREN, a 3-by-6-inch device that screws onto ceilings like a smoke detector. It’s equipped with a microphone and a computer program trained to identify a gunshot, and with multiple devices located across a school, it can pinpoint exactly where a shot is coming from. Within five seconds, SIREN can send a map of the school — and the location of the shot — through an SMS message to all students, teachers, staff and the local police department.

“In situations like this, miscommunication can be really dangerous,” said Srivastava. “What we learn in school is to run, hide and defend. But we can’t do any of that if we don’t know what’s going on.”

Police across the Bay Area have had success with ShotSpotter, a similar device that’s been on the market for decades. The technology works through a set of acoustic sensors on streetlights or telephone poles, which are connected virtually to a cloud-based platform. Once a gunshot sounds, the sensors can triangulate its location and send the recording to a team of human experts. They then verify that sound and alert law enforcement within 60 seconds.

The timing of that response, the SIREN team said, is essential. The average school shooting lasts 12.5 minutes, while the average time it takes police to arrive is around 18 minutes, according to the National Sheriffs’ Association.

“Anything we can do to better improve our response time, get to a victim faster, and make the public safer, we’re 100% on board with,” said Sgt. Adam Lobsinger, the public information officer for the San Francisco Police Department. “Whatever these kids are doing to improve (technology like) ShotSpotter is a good thing.”

David Riedman, the founder of the K-12 Shooting Database, agrees the impact of SIREN — if it works as intended — could be immense. Today, he said students are often told two different things during a school shooting: to run or to hide. But without knowing exactly where the gunshots are coming from, administrators can’t give proper guidance on what students and staff should do to escape or to protect themselves.

“You need to know whether there is an imminent threat or not,” said Riedman. “Is it best to get away, or stay where I am? Right now, that’s often a guessing game.”

With the constant uptick in gun violence, Wang’s team feels they can’t move fast enough. From 2013 to 2023, the number of times a gun was brandished or fired on school property nationwide skyrocketed by nearly 800%, as reported by the K-12 School Shooting Database — from 34 to 304 incidents in 10 years alone.

“As students, we definitely worry. Is it going to happen to us next?” said Audrey Wang.

Across the country, students, teachers and parents have tried to sound the alarm on school shootings — including those across the Bay Area. Late last month, students from Willow Glen High School in San Jose led a walkout after a student brought a loaded gun to campus, the latest in a string of similar events across the district. At a packed school board meeting the day before the protest, students, teachers and parents expressed their concerns.

“As a student in high school, I shouldn’t even be worried about getting shot up at school,” said Mar Lopez, who spoke at the school board meeting. “Do you want my peers to die? Do you want the blood of others on your hands?”

For Gerson Castro, a history teacher at Gunderson High School, the SIREN project is just another example of students having to shoulder a burden that shouldn’t be their own. He was impressed by Wang’s idea, along with her team’s ability to bring it to fruition — but he wished they didn’t feel they had to.

“It’s just so sad that these kids are using their intellectual talents to come up with something that the adults in the room aren’t doing a better job of addressing,” said Castro.

Their efforts are gaining attention. Earlier this year, the team won the top prize in the cybersecurity category of the Conrad Challenge, a prestigious innovation competition that attracted nearly 1,000 student teams across the globe. They exhibited their work at the NASA Space Center in Houston. And now, they’re looking for investors and police partnerships to take SIREN to the next phase of development. Though Wang says their prototype has a 99.3% accuracy rate when compared with audio of gun-like sounds, they’re now ready to test their device using real guns — and eventually, take their product to the market.

“This is their normal, even though it shouldn’t be,” said Castro. “What (these students) have done is they’ve given the people on campus a chance.”