Authorities say the student who opened fire on a Nevada middle school campus, wounding two students and killing a teacher, got the weapon from his home.
Washoe County School District Police said Tuesday they are still working to trace where the gun was bought.
Police said a Sparks Middle School student was the lone shooter and killed himself.
Police say 45-year-old math teacher and former Marine Michael Landsberry tried to stop the rampage before he was fatally shot.
The two boys who were shot are stable and recovering.