Students in Florida and Washington, D.C., protest gun violence

Lital Donner, youth director for Congregation Kol Tikvah in Parkland, Fla., comforts Aria Siccone, 14, a ninth-grade student survivor from Marjory Stoneman Douglas High School, where 17 people were killed in a mass shooting. Aria told her story of surviving the deadly shooting to state legislators in Tallahassee, Fla., where she was joined by hundreds of students and other activists challenging lawmakers on gun control reform.

Lobbyists and attorneys listen as student survivors from Marjory Stoneman Douglas High School, where 17 students and faculty members were killed in a mass shooting last week, interrupt a house legislative committee hearing to challenge lawmakers on gun control reform in Tallahassee, Fla.

Julia Salomone, 18, left, and her sister, Lindsey Salomone, 15, student survivors from Marjory Stoneman Douglas High School, hug as they march to the state Capitol to demand gun control reform in Tallahassee, Fla.

Hundreds of protesters gather at the Florida state Capitol in Tallahassee to push for legislation regulating assault-style weapons and guns in general, after 17 people were killed by a gunman at Marjory Stoneman Douglas High School in Parkland, Fla.

Students from Montgomery County, Md., in suburban Washington, D.C., rally in solidarity with those affected by a mass shooting at a high school in Parkland, Fla., a week ago.

Students protest gun control at the Capitol in Washington, D.C., one week after a mass shooting at a high school in Parkland, Fla., killed 17.