Tens of thousands of students across the U.S. joined in a collective action on Wednesday, April 5, at noon local time, and walked out of their classes en masse to demand gun control legislation.

The student participants spanned geographical location—from Oregon, to Texas, to Massachusetts—and age, ranging from elementary school to high school and beyond. Some demonstrations were frantic and loud, with urgent chants directed to lawmakers and gun manufacturers: “Our blood, your hands.” “Books, not bullets.” “Hey, hey, NRA, how many kids did you kill today?” Others were silent and somber.