Teachers at Florida's Marjory Stoneman Douglas High School demonstrate outside the school before classes ahead of students' National School Walkout relating to gun reform on Friday, April 20, 2018.
CNN  — 

The principal of Marjory Stoneman Douglas High School, where 17 people were killed in a February 14 school shooting, said students who walk out today will be punished.

Principal Ty Thompson told the students during Thursday’s announcements that if they leave campus they will face disciplinary action. A teacher told CNN that the disciplinary action will be an unexcused absence.

But that didn’t stop students who nevertheless participated.

Most of the teachers had said they expected a good number of the students to walk out of the classrooms, but they aren’t so sure how many will leave campus.

However, the student body isn’t exactly unified on this walkout. While many of the most vocal students are promoting the walkout, some other students feel conflicted since the walkout marks the Columbine shooting anniversary. Columbine leaders have pushed back against a walkout, asking students to treat the day as a day of service and not just a day to walk out.

At Stoneman Douglas, some of the students worked on acts of service on campus instead of actually walking out, principal Thompson tweeted.