The mass shooting at a Florida high school that left 17 people dead has sparked calls for walkouts, sit-ins and other actions on school campuses across the United States aimed at pushing lawmakers to pass tougher gun laws. Organizers behind the Women’s March, an anti-Trump and female empowerment protest, called for a 17-minute walkout on March 14 to “protest Congress’ inaction to do more than tweet thoughts and prayers in response to the gun violence plaguing our schools and neighborhoods.” The Network for Public Education, an advocacy organization for public schools, meanwhile, announced a “national day of action” on April 20, the anniversary of the 1999 shooting at Columbine High School in Colorado, in which two students opened fire on their classmates, killing 12 students and one teacher. The organization is encouraging teachers and students to organize sit-ins, walkouts, marches and any other events to protest gun violence in schools. “The politicians sit on their hands as our children and their teachers are murdered in their schools,” Diane Ravitch, the group’s president, and Carol Burris, its executive director, said in a post online. The protest plans circulated widely on social media on Saturday, signaling that the outcry for new gun legislation may not fade away as it has after other recent mass shootings.