Starting with yet another school shooting. This one at Seattle pacific university, where student heroes came to the rescue with a dramatic takedown of the shooter. Neal Karlinsky has all of the... See More
Starting with yet another school shooting. This one at Seattle pacific university, where student heroes came to the rescue with a dramatic takedown of the shooter. Neal Karlinsky has all of the latest. Good morning, Neal. Reporter: George, good morning. Police say the gunman walked through that door over there and opened fire when he got inside, just as students were taken their final exams. We have a suspect who is down and needs medical attention. Reporter: Chaos on a college campus. A halo of shotgun shells. Reporter: It was just before 3:30 in the afternoon, when police say Aaron Ybarra walked into Seattle pacific university and opened fire with a shotgun. This student's friend was hit. I got one text message from him. He just said, I got shot. And I texted him five or six times. But I got no response after that. Reporter: Students, huddled in locked classrooms. One stood guard inside with a pipe in his hand. We thought it was an experiment at first. But then, we heard screaming. Reporter: Out in the building's lobby, police say Ybarra fired on three students. But when he stopped to reload, students say a building monitor, seen here, risked his own life, pepper spraying the suspect, and jumping on him. He has a fiancee. He has a lot to live for and acted quick. Reporter: Other students held Ybarra down until police arrived. His gun seen here on the ground. My first reaction was heartbreak that a senseless act would have happened on this campus. Reporter: Chris Howard tried to help a woman who was shot, cradling her head in his lap. She was panicking. Call my mom. Call my aunt. Call my best friend. I need you to make these calls for me. Reporter: A man in his 20s was killed. Two other victim, a man and woman in their 20s are hospitalized with shotgun wounds. As for Ybarra. Open the door. Reporter: ABC news was there when police stormed his parents' home late Thursday night. Authorities say he is not a student at psu. His connection to the school, unknown at this time. This could have been so much worse, if not for that brave student who leapt into action, armed with only pepper spray. As for the suspect, he has been booked on investigation of homicide. There is no known motive for this.
This transcript has been automatically generated and may not be 100% accurate.