'Heroic' bystander who stopped suspect in Oregon elementary school shooting IDed

Out of the urgent investigation of a deadly mass shooting at an elementary school in Oregon yesterday, three students and a teacher were killed before a bystander shot and killed that suspect. ABC's Alex Stone now with the latest from Bend, Oregon. Investigators are here on scene and they are trying to piece together why and how the 16-year-old arrived here at this elementary school and went in and opened fire, killing three students, a 5-year-old, an 8-year-old, and an 11-year-old, and a teacher, and injured another student, and a teacher as well, who were seriously injured. A lot of questions the police have. We have seen them in the woods around us with their dogs out today, looking for evidence. We are learning more about the Good Samaritan in this, the man who went in and stopped the shooter, according to police. His name, Caleb Giamonco, the father of two students at this school, that according to his family, he heard commotion at the time the shooting started. He went in. He's a concealed weapons holder. He had a gun, and he killed the shooter and stopped the shooting from happening in that moment. According to his family, he is regretful, and he is saddened that he wasn't able to save more lives, those who were killed, that he didn't move quicker and go in there. But they say that also he is very thankful to all the first responders. But to give you an example of how quickly this all went down, the first 911 calls came in. Three minutes later, police were on scene, and within those three minutes, The shooting had started to when the shooter was down and had been killed by Giamonco. So he acted very, very quickly as he came in and knew something was wrong here at this school. But investigators say still a lot they've got to learn about this situation. Alex Stone, ABC News, Bend, Oregon.