While some students screamed or prayed as a gunman shot and killed 17 people in a Parkland high school, a few pulled out their cell phones to show the world what was happening.
"Oh my god," one student screams in a Snapchat video, which shows students screaming in a classroom, as gunshots echo outside.
From the chaos came quiet as other students on Twitter posted haunting still shots from under their desks. In some, teens messaged friends and family, while others posted pictures with captions telling followers they were safe.
Outside, the snaps come fast and furious, spreading images of choppers and tears, but also videos that appear to show officers arresting someone a few blocks from the school.
"This is the site that he got caught," the poster says off-camera.
Police arrested 19-year-old Nikolas Cruz, a former student expelled for disciplinary reasons.
The sheriff says investigators are checking into his social media accounts. An Instagram account with the same name shows a person in a mask in the profile picture. A small number of posts are seen including guns, ammo and a dead frog, with the caption #killingtoads.
By 6 p.m., the account was deactivated.
Later in the night, even more social media posts went viral.
Some were reflective, others hopeful, like one video, which shows a child is reunited with a loved one.
Football players from the school also took to Twitter asking for prayers for "Coach Feis," who they say was shot, shielding students from gunfire.