lowest level since november 20 2008. We move next about a 12-year-old boy who opened fire in a middle school in reno, nevada. That teacher, the former marine who tried to stop him. Eye witnesses are... See More
lowest level since november 20 2008. We move next about a 12-year-old boy who opened fire in a middle school in reno, nevada. That teacher, the former marine who tried to stop him. Eye witnesses are coming forward to describe how a valiant sacrifice saved lives. Here's abc's cecilia vega. Reporter:911 emergency? I'm calling from sparks middle school. We have a shooting at our school. Reporter: The rampage lasted just three minutes. This is a student from sparks middle school. Can you please send police out here. There is a kid with a gun. Reporter: That kid, a 12-year-old boy in the 7th grade. Police believe he got that gun from his own home. He opened fire near the basketball court just before the morning bell, using a nine millimeter semiautomatic ruger hand gun similar to this. His first victim, another 12-year-old shot in the arm. He went like that with the gun and pulled the trigger. Reporter: Then the shooter turned to the teacher who tried to stop him. 911 emergency. Somebody brought a gun to school. They shot a teacher. The teacher is down? Yes. Reporter: Students saw michael landsberry, a former marine who served in afghanistan down and they ran toward the gunfire to help. We tried lifting him up. He was like this, like trying to hold his wound, like holding it. Reporter: Another boy shot in the abdomen. He's in stable condition. Then the shooter turns the gun on himself. Faith evans had math class with him. Did he have friends? Sort of. He got bullied a couple times and I saw kids pushing him around and doing mean things to him. Reporter: Now there is just one question. Everybody wants to know why. The answer is we don't know right now. Reporter: Police say they have no plans to release the shooter's identity out of respect for his grieving family. Since police believe the gun he used may have come from his house, authorities are looking into whether his parents can be charged. Diane? As you said police believe the 12-year-old shooter may have taken the gun from his own home. Here's a something to keep in mind. One third of american families have a gun in their home.
This transcript has been automatically generated and may not be 100% accurate.