The students of Marjory Stoneman Douglas High School in Florida returned to campus Monday after their spring break, as a slew of new security measures took effect — including a rule requiring clear backpacks.

The backpacks, according to the Sun Sentinel, were donated to the Parkland school’s student body of 3,200 free of charge.

The updated attempt from Broward County school officials to strengthen security and make it more difficult for people to smuggle weapons onto campus came more than a month after the massacre that killed 17 people there.

Confessed gunman Nikolas Cruz told investigators he “brought additional loaded magazines to the school campus and kept them hidden in a backpack until he got on campus to begin his assault,” the Broward County Sheriff’s Office said. He also was able to hide his AR-15 in a bag, officials added.

Teacher Jim Gard said after the Feb. 14 mass shooting that he believed the high school sent out an email warning teachers that Cruz shouldn’t be allowed on campus with a backpack.

In a memo to parents, Stoneman Douglas Principal Ty Thompson said the enhanced security measures would be “very similar to when you enter a sporting event, concert, or even Disney World.”

To enter campus, students now are allowed through four monitored gates before school starts, and only one after the opening bell. The school district plans to issue metal-detecting wands to law enforcement officers stationed at the gates, and sports bags and musical instrument cases are subject to search.

Additional security precautions include stationing eight Florida Highway Patrol troopers at the school, locking classroom doors “at all times,” securing outside doors and gates often, and “conducting emergency preparedness and response training for faculty, staff and students on a regular basis.”

Students also will get identification badges and lanyards to wear by the end of the week, officials said.

But some students claimed the bolstered security, particularly the use of clear backpacks, wouldn’t bring a better sense of security, but instead would make them feel uncomfortable.

“I think it’s the illusion of security, and it’s not going to accomplish anything, except make students feel like their privacy is being violated,” student Kyrah Simon told the newspaper.

Another student, 16-year-old Kenya Warner, said she thought, “if people want to bring weapons to school, they’ll find a way, and clear backpacks are not going to solve anything.”

Sarah Chadwick, a Stoneman Douglas student and member of the March for Our Lives movement, tweeted that the latest measures were starting to make school “feel like a prison.”

Student Kyra Parrow wrote the backpacks and lanyards were “just an illusion of security,” while Delaney Tarr, also a prominent face of the students’ gun control movement, called them “a good ol’ violation of privacy!”

Superintendent Robert Runcie told the Sentinel that the new backpacks were “an initial measure, not a permanent one,” and noted that Broward Schools would consider allowing other backpacks after seeing how well the metal detection wands worked.

The Associated Press contributed to this report.