#12 Just Another Hero (The Jericho Trilogy Book 3) by Sharon M. Draper
Description of the book:
This group of friends has been through so much after a deadly hazing ritual left friendships broken, hearts aching, and November pregnant with Josh’s baby. But senior year is going well, and when the fire alarm goes off, everyone assumes that crazy Jack is trying to get out of a quiz or a test. Then he shows up at the science lab wielding an AK-47, sputtering about the need to finally be taken seriously. There’s only a matter of seconds to stop a tragedy, and all eyes are searching for someone—anyone—to step up to be the hero.