Nightly News | December 14, 2013
>> one-year anniversary of the newtown school massacre. we're learning details of the latest act of school gun violence . this one yesterday in a denver suburb that left a teenage girl badly wounded and the shooter, a fellow student, dead. police say it all happened in just a minute, 20 seconds. 18-year-old karl pierson marched into his school with a shotgun, a machete, and molotov cocktails in what may have been conceived as an act of revenge. but offici -- nbc's ron mott is live for us with more. good evening.
>> reporter: hey, lester. good evening. police say they have a lot of work ahead in this investigation and they'll take their time to do a thorough investigation but did release new details just late this afternoon. they tell us that karl pierson legally bought this pump-action shotgun just a week ago yesterday and that this shooting took place very, very quickly. they say the time from when he walked into the building, the north entrance to this school , and the time he killed himself, police say took all of 80 seconds. officials say karl pierson 's target was the debate teacher who students say kicked him off the team earlier this week. a school librarian was seen with police late last night. even though it appears pierson acted alone, law enforcement worked overnight at what they called four crime scenes. the school , the suspect's car, his house, and his father's home. tonight, authorities are getting a clearer picture of events leading up to friday's shooting but are still trying to determine why the 18-year-old senior resorted to violence, armed with a shotgun, multiple rounds of ammunition, a machete, and three molotov cocktails .
>> it is our strong belief he came to this school with that weapon and with multiple rounds and his intention was to utilize those multiple rounds to cause harm to a large number of individuals.
>> reporter: with their school surrounded by yellow police tape again today, students returned to retrieve their cars, still unnerved by the terrifying moments that unfolded here yesterday.
>> i see two shotgun shells on the ground here.
>> reporter: captured in cell phone video from inside a classroom.
>> yesterday was chaotic. i don't know. i just didn't really feel real.
>> reporter: police say pierson died from a self-inflicted gunshot wound as authorities moved in, but not before cops say he shot fellow student 17-year-old claire davis at point-blank range.
>> she was an innocent victim of an evil act of violence .
>> i have a student down in the athletic hall.
>> reporter: 10th grader delaney mullins and a friend heard the shot, ran from the library, and passed the bleeding girl critically injured on the floor.
>> it was extremely smokey, so i couldn't see anything except a girl who had just been shot. she was falling to the ground and there was blood on the floor.
>> reporter: by most accounts, pierson was a likable and sociable student. a talented debater who competed at the national level, a cross country runner , someone who voiced political opinions. these sophomore twins were pierson 's teammates.
>> he was a very likable guy. really good friends with all the coaches. as far as i'm concerned, he had a lot of good friends on the team.
>> he's a normal student. he participated in class, very intelligent.
>> reporter: there is a candle light vigil here in town tonight. as for claire davis , she had surgery yesterday. she is in critical condition. the police emphasized they could find no connection between claire davis and this shooter karl pierson , she just happened to be at the right place at the wrong time. school will not have classes on monday. the superintendent said it's unlikely they'll hold any normal school activities