CENTENNIAL - Arapahoe High School students and staff were expecting an uneventful end to the school week, but gunshots shattered that expectation Friday afternoon.
Fabian, an Arapahoe High School janitor, says he saw the shooter right before he entered the school.
"I was turning the corner when I saw a kid running into the north side of the building," he said. "He was kind of running side-to-side, military-style, when I saw that, I double looked to see if it was a gun. It looked like a shotgun. So, right away I got on the radio to alert everyone."
Fabian says the gunman entered the school and headed toward the library in search of teacher, and then fired at him but missed.
"He was so [shaken] up, he felt the wind hit, out of the shotgun just blew his hair out but it didn't hit him. It was that scary for him."
Alex, an Arapahoe High School Junior, says at first he didn't recognize the loud noises as gunshots.
"I just thought they were books dropping, " he said. "So our teacher after the shots were fired told us to go to the corner of the room and at that point I knew it was a serious situation."
Witnesses who drove by the school around the time of the shooting say it was very chaotic. A grandparent of student says he saw concerned parents arriving at the school, some of them were in full scrubs, others in workout gear indicating they dropped everything to get to the school as quickly as they could.
Student Jack Berrning says he was sitting in class when they heard gunshots.
"First we were just sitting there in class having a discussion, I don't remember about what, and then we heard gunshots one, two three," he said. "Everyone just looked at each other, and we just kinda knew that it was real."
He says he and his classmates took off to the back of the classroom as they heard more gunshots.
"The lights went off, and before I knew it, we were all scrambling to the back of the classroom. We got there really quickly," he said. "There were more gunshots happening."
When the shots stopped, he says there was a lot of chaos.
"Just a lot of commotion as well as a lot of silence in our classroom. Everyone was so scared, Every girl in the classroom was crying. I was just freaking out," he said.
Another student, named Holly, says her classroom is right near where the gunman entered the school.
"We were just sitting there reviewing for finals and our door was open, our teacher was actually outside the classroom talking to some students and we heard two very, very loud gunshots", she said.
She says her teacher immediately jumped into action to protect them.
"She closed the door, we ran into the corner, dove on top of each other just tried to get behind the desks. Obviously a very terrifying thing."
After about 30 minutes, Holly says she and her classmates were escorted out of the school by law enforcement.
"Leaving the building it was very troubling to see blood, blood stains on the floor on the carpet," she said.
She says she's still in shock.
"It still hasn't really hit me, uh that it happened at my school and that my school is now a crime scene," she said.
Ben was in chemistry class when the shooting starting.
"Three or four students came in from the office and they just said get down we don't know what happened. We heard some loud noises we're just going to treat it as a lockdown and then they came on the announcement said it was a lockdown. Within in minutes there just sirens everywhere."
Ben says all the students hid in the classroom so that if the gunman looked through the window door they wouldn't be seen.
"They had us get as far away from the doors and windows so that if someone were to look in the door they could not see, turned off all the lights and just be as quiet as you can," he said.
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