Burlington Police are investigating a student who brought a gun to school.

It happened Monday at the Horizons program, Burlington's alternative high school.

The principal tells WCAX News that school officials were searching students' backpacks after a report of a missing cellphone and came across the weapon.

The school went into lockdown at about 12:30 p.m. and Burlington police responded.

Principal Bobby Riley says the student-- whose name is not being released-- did not say why they had the weapon, but it appears the student had no intention of using it.

In a letter to parents, Riley said there was no immediate threat to students or staff.

"The trainings that we do, they're for a purpose. And they served that purpose in this most recent incident. Students were secured quickly. They didn't know what was going on in the moment. They continued with their day. Staff remained calm. Again, practice does set us up for these things, as unfortunate as they are, but the reason we do these drills is so that when incidents like this do occur, they go off without incident," Riley said.

The principal says staffers later offered counseling to students to talk about what happened. Riley says Burlington School District councilors will be at the school for the next few days for more one-on-one sessions.