The city’s decision to install metal detectors in its 13 public high schools might be paying off.

The new metal detector system, which was put in place earlier this fall after a summer of increased gun violence, recently faced one of its first tests at Wilbur Cross Annex High School. On Oct. 20, a freshman at Cross Annex attempted to smuggle a loaded gun into school in his backpack, according to a press release from the New Haven Mayor’s Office. But a security guard noticed a suspicious item in the bag and detained the student, who refused to have his backpack scanned by the metal detectors and then fled from the building with it. The student was later arrested and the Cross Annex student body went about their day unharmed.

The security response was swift and effective, city officials said, and they credited the metal detectors with effectively preventing a firearm from entering the building.

Smoking cigarettes and laughing in the Cross Annex parking lot during lunchtime, underclassmen Luis Cartagena and Hector Rodriguez said they are not nervous about the threat of guns at their high school. The success of the metal detectors eases their concerns about school safety, they said.

“I always feel safe here,” Cartagena said. “They got it covered. I’m not worried coming to school.”

But other students said their fears were not so easily assuaged by the role of the metal detectors in preventing what authorities said could have been a dangerous situation. Although the revolver never got past the security checkpoint, some students at Cross Annex said they are still not convinced that the metal detectors are the most effective means of policing the school.

“It’s good that they got them in there and that they’re trying,” Cross Annex student Jennifer Fuentes said, laughing at the proposed security plan. “[But] those metal detectors don’t even work. And they don’t check people right.”

Some students said the metal detectors are insufficient in detecting crime and advocated a system with more vigilance from human eyes than from machines. They said that the metal detectors are a good idea, but that they do not feel safe because the security system does not check everyone properly.

For many, the metal detectors are more a symbol of security than an effective checkpoint. Students and visitors often enter the building outside of the metal detector archway, unnoticed and unchecked. In Cross Annex, security personnel — such as the guard who noticed the firearm on Oct. 20 — are present near the metal detectors at the school’s rear entrance, through which students and guests are supposed to enter.

At Cross Annex and some of the larger high schools, students walk through an airport-style security system, New Haven Public Schools Superintendent Dr. Reginald Mayo said in a letter sent home to all parents at the beginning of the school year. But at smaller schools, security guards are only equipped with wands and may use them sporadically, said Catherine Sullivan-DeCarlo, spokeswoman for Mayor John DeStefano Jr.

Especially at lunchtime, when students are allowed out to the parking lot and surrounding streets, students at Cross Annex said, they would feel safer if the metal detector system were enforced more consistently.

“They’ve got to pay more attention,” student Jeraya Hall said. “They’ve got to get more teachers out there looking out for us. The way they’ve got it now, I don’t feel safe here.”

Sullivan-DeCarlo said the students’ concerns about the metal detectors’ inadequacies are well-founded, since metal detectors alone would be a “pathetic” means of security. But this is not the only safety precaution that New Haven public schools are taking, she said. Along with the metal detectors and school security officers, the schools implement programs like the Social Development Program to teach the students about safety and how to deal with possible threats, she said.

“We try to create a climate so that students know that if something weird is going on, that there are lots of adults around and they feel comfortable telling an adult about a problem,” she said. “We offer a whole host of programs for security and safety.”

Cross Annex Assistant Principal Janie Holmes agreed that the metal detectors alone could not ensure school safety. She said making sure students can learn in a safe environment requires a combination of security measures. While technology can play a role in ensuring student safety, she said, students need to alert teachers to possible threats.

“I think it takes a composite of things,” Holmes said. “It takes metal detectors, alert security people and students being a part of the vigilante.”

Sullivan-DeCarlo said many other districts in Connecticut, including Bridgeport and New Britain, are now wrestling with the decision to install metal detectors in their high schools.