Lockdown

"Some days it's just easier not to go to school at all. Adam has been slacking off lately, but today he stuck around to see his girlfriend. When Josh, who has been bullied mercilessly, brings a gun to school, the building is locked down and Adam is forced to risk everything to save himself and to find Zoe before Josh does. Calling on reserves he didn't know he had, Adam could end up a hero—or a victim."

Summary from Orca Book Publishers:

https://www.orcabook.com/Lockdown-P303.aspx