A Roosevelt High School student wears a sticker saying she'll be able to vote this year as hundreds of high school students participate in the National School Walkout to protest gun violence at the University of Washington in Seattle, Washington, U.S, March 14, 2018.

Students from Marjory Stoneman Douglas High School and Westglades Middle School gather near memorials at a nearby park where they marched as part of a National School Walkout to honor the 17 students and staff members killed at the school in Parkland, Florida, U.S., March 14, 2018.

Students holding protest signs walk the perimiter of a rally held at the Prospect Park Bandshell for the National School Walkout in Brooklyn, New York, U.S., March 14, 2018.

Students from Broward County high schools stage a die-in on a sidewalk in downtown Fort Lauderdale, Florida, U.S. March 14, 2018.

People supporting gun control attend a hearing by the Senate Judiciary Committee during a hearing about legislative proposals to improve school safety in the wake of the mass shooting at the high school in Parkland, Florida, on Capitol Hill in Washington, U.S., March 14, 2018.

Students from local high schools file into Red Square at the University of Washington as they participate in the National School Walkout to protest gun violence in Seattle, Washington, U.S, March 14, 2018.

Columbine High School student Leah Zunder holds a sign during a National School Walkout to honor the 17 students and staff members killed at Marjory Stoneman Douglas High School in Parkland, Florida, in Littleton, Colorado, U.S. March 14, 2018.

A student bows her head as the group holds a minute and seventeen second period of silence during the National School Walkout to protest gun violence in at Roosevelt High School in Seattle, Washington, U.S, March 14, 2018.

Students holding signs in honor of the victims of the Marjory Stoneman Douglas High School wait before taking the stage during a rally held at the Prospect Park Bandshell for the National School Walkout in Brooklyn, New York, U.S., March 14, 2018.

Students take a moment of silence outside Crescenta Valley High School as part of a National School Walkout to honor the victims of the shooting at Florida's Marjory Stoneman Douglas High School, in La Crescenta, California, U.S., March 14, 2018.

Students from Gonzaga College High School in Washington, DC, hold up signs with the names of those killed in the Parkland, Florida, school shooting during a protest for stricter gun control during a walkout by students at the U.S. Capitol in Washington, U.S., March 14, 2018.

Marjory Stoneman Douglas High School student Lenore Munoz, 17, speaks to a crowd of students after they marched to a nearby park as part of a National School Walkout to honor the 17 students and staff members killed at the school in Parkland, Florida, U.S., March 14, 2018.

Roosevelt High School student organizers Scout Smissen, 17, and Gabe Rosenbloom march with Zach Heffron, 18, of Nathan Hale High School as they march with hundreds of other students to the University of Washington in the National School Walkout to protest gun violence in Seattle, Washington, U.S, March 14, 2018.

Students participate in a march in support of the National School Walkout in the Queens borough of New York City, New York, U.S., March 14, 2018.

Students from Washington, DC-area schools protest for stricter gun control during a walkout by students at the U.S. Capitol in Washington, U.S., March 14, 2018. REUTERS/Joshua Roberts