(UPDATED, Wednesday, March 7, 1:20 p.m., to reflect revision in policy.)

Caldwell High School instituted a no-backpack policy this week.

But even before the Wednesday rollout, the policy was changed.

On Monday, the school said students would be assigned lockers at no charge, and would be allowed to carry bags only the size of an 8 ½- by 11-inch piece of paper. Under the new policy, students must check in athletic bags with gym teachers in the morning, or store them in their cars.

By Tuesday, the school retooled the policy somewhat.

“Students will be allowed to bring backpacks but they must be placed in lockers upon arrival at school,” according to Caldwell’s Facebook page. “Backpacks cannot be worn during lunch or in class or passing periods.”

The move comes after local police have investigated threats at four area schools. Caldwell High School canceled classes on Wednesday after a campus threat, the Idaho Press-Tribune reported.

“I’m supporting the high school and this effort,” Caldwell Superintendent Shalene French told the Press-Tribune. “I think that they’re working to keep students safe.”

The change sparked a heated debate on the school’s Facebook page. Some students and parents said the change would not make the school safer. Other commenters commended the school for responding quickly, in the wake of the Feb. 14 mass shooting at a Parkland, Fla., high school.

One commenter — identified as Melissa Ann — described herself as a Caldwell graduate now living in Parkland.

“I honestly CANNOT believe people are arguing this!” she wrote. “If you would like to come and visit our 17 families and community of heartbroken citizens, we would welcome you, and then you may think differently about a no-backpack rule.”