Alexandria, Va., photographer Jeff Olson joined an estimated crowd of more than 800,00 at the March For Our Life rally Saturday in Washington, D.C., as students gathered in the nation’s capital and at sister marches all across the United States  to deliver a powerful, unified message: Enough is enough. The rally, organized by students from Marjory Stoneman Douglas High School, the site of a shooting last month that claimed 17 lives, was part of a nationwide movement for gun reform.