Transcript for PA School Stabbing Suspect in Police Custody
This is a special room. I'm Michelle Franzen in New York a mass stabbing at a high school in Western Pennsylvania this morning. At least twenty people reported injured from teen students to an adult security guard. The suspected attacker a sixteen year old student now in police custody. More details now from ABC's -- Ferris. Probably would want to know god -- it. Here's one of the victims being taken out on a stretcher. As aerial footage shows students -- evacuating and buses lined up. My friend -- said. He just saw him running with a knife and eight -- -- turn the corner and there is some kids like holding their stomach with blood everywhere the whole not the whole science wing was just. Chaotic and crazy. The attack happened early this morning around seven -- -- before classes had even started at Franklin high school located just east of Pittsburgh. Which is home to 12100 students eyewitness reports -- that lone suspect a student at Franklin high was running around stabbing people. And there was crying and screaming and the whole ways. The officer that time had the subject the sixty year old subject in custody in hand we had eight victims brought -- hospital. Three of those patients had severe injuries and are actually still in the -- room right now. To those patients are critical condition they have stabilized frantic parents were told to -- at home. She was crying as she told me to get down here now. Either my wife -- or to get down very bitter -- no little thing though -- to prepare was anything like this. And the worst campus. So that the townspeople. Paula -- -- ABC news New York. And we're now joined from Washington DC by ABC news consultant to former FBI agent Brad Garrett Brad thank you very much. The student suspects has been in custody for a few hours now. If you're interrogating him what are your first questions that you're going to ask. Well you know one of the real teases kit will he does he want to talk to you and so you may have to spend big period of -- -- -- getting too. What are his issues and hot buttons. He would then we'll go to. You know what would set you off here where. What was -- what was the purpose of doing this and there's going to be a lot of anger and rage but you sort of have to get into his reality sometimes -- get him to talk. In a way to tell you the truth. And there's a lot of things going on here obviously and very fluid type of crime scene going from. Sounds like hallway to hallway classroom to classroom. And you know -- you do want to get at some point to his motive. And Brad this police are giving NASA few details saying the suspect had two knives -- -- suggest anything to you about intent. The potential was -- pre planned. What -- police are looking. Well. -- be -- -- wasn't pre plan that may not have been pre planned for. Days or weeks but he he certainly thought through when he was gonna do this how we was gonna do this because. Even the way he did -- and other words stabbing people it's been reported possibly with two knives -- -- -- for maybe one in each hand. He's on the move. And that I think allowed him to keep moving if you were stayed in one location somebody probably would have tackled him. But that you -- you you have to go through an -- and get from him hopefully is. What was the point of this or did you go after one person and then didn't become a Rampage after that. And of course one of the things authorities will be looking into is this the psychological. Any background into the student any potential problems. Give me an idea though does knife violence differ from a gun violence beyond the obvious choice of weapon. Well and in no way in other day and -- is a lot more personal than going through and shooting people -- you literally have to be on top of them shooting you can be a distance away. It also would suggest. That he wasn't after the same level of mass casualties -- -- then a school shooter with typically go after. But having said that obviously he's injured now twenty people some critically so he had a fact. Just as have the same impact on the school that a school shooter would have. And we were told that the assistant principal attacked and tackled the attackers stopping. The attacker from going further. What other details could we learn about this that could shed lights -- obviously this happened early in the morning there may have been security measures in place at the school. Well there's two things you gonna -- up 41. Was in -- earlier was there any signs that this was about to occur. There words heady talk to another student about harming someone or that he had -- -- with -- particular teacher. Or student. Heading written about it -- he acquired in -- recently some of these things you may or may not know as a as a school administrator. And -- that then after that they're gonna have to look at this from an after action -- point. Was pulling a fire alarm the best way to handle this I'm not being critical of anybody at this point but think about it and then -- school shooter or. A mass -- like this guy was when you flood the hallway you actually giving potentially more targets so again we'll have to see how the dust settles with the split. Looking at how they responded to it may Alter how schools respond to similar situations. In the future. And of course we've had several school incidents of school violence varying from. You know guns to other types of violence. We're also told the FBI is also on scene even though the local police have the jurisdiction here what might they be helping out with here. -- really support. At this point do they need additional people to process the crime scene every major FB office has an evidence response team. Supplying any additional lead information in other words if the if it if the sixteen year old custody has a history in another state or another jurisdiction. They're gonna pull those records for them because they can get to them quicker. That sort of thing and I suspect that's world will stop because usually -- school shooters in this case the school staffer. It's pretty much a local event -- so they're really just there for support. Brad Garrett from Washington thank you very much for joining us. You can of course keep up with the story in real time by downloading the ABC news apps starring this story for exclusive updates on the go. For now I'm Michelle Franzen in New York.
This transcript has been automatically generated and may not be 100% accurate.