I'm Anderson Cooper, welcome to podcast, at 360 exclusive, he came face to face, eye to eye with a rifle-wielding student, and lived to tell about it, possibly prevent the murder of other students, also the ridiculous, let's get started.

Tonight we're learning just how close the University of Central Florida came to a massacre. Today campus police released this video, showing the moment they entered the dorm room where a 30-year-old former student still living on campus had just committed suicide. And once inside, officers not only found his body. They also said they found an Arsenal, guns, ammunition and explosives along with chilling checklist suggesting that that guy is one step away from a rampage on massacre scale. The officers were there responding to a 911 call from his roommate, who I spoke with just a short time ago, today we're going to bring you that exclusive interview in a moment. But first, Ed Lavandera takes a closer look at exactly what happened there.

Just after midnight on Monday, the fire alarm starts blaring inside this dormitory at the University of Central Florida campus. Arabo Babakhani calls 911 after he looks out of his bedroom to find his roommate pointing a gun right at him.

"My roommate pulled a fire alarm and he's got a gun out."

"All right, where are you at?"

"I'm in the University of Central Florida in Orlando, the fire alarm went off, I opened the door to see what's going on, and he's there with like, some sort of like, gun, like large assault gun, I don't know if it's a real gun, I don't know what it is, I just saw it and slammed my door shut and locked it."

"Are you in your room now? Secure in your room?"

"Yeah, I'm in the bathroom."

When campus police arrived to the scene, they make their way to the gunman's dorm room. This might be disturbing for some to watch, but police found 30-year-old James Oliver Seevakumaran lying dead on the floor, from a self-inflicted gun shot wound to the head. They also found that he apparently was planning a massacre. Police say there were four homemade bombs inside a backpack, multiple fire arms, and hundreds of rounds of ammunition.

"I don't think that you acquire 210 round magazines and numerous 22 capacity magazines, and that you purchase a 1000 rounds of ammunition, and that you purchase the 45 ammunition, I don't think you just do that as a joke."

Investigators also say the found this writing on a piece of paper laying out a sort of a timeline of what Seevakumaran planned to do. Scratching off items as he went down the list. The first item on his list was to go to this bar called the Mad Hatter, across the street from the campus, to first, quote, "get drunk, then get equipped, take a shower and shave up." The note reads to put on YouTube, and instructions to pull the alarm and the item read, good luck and give them hell."

"There is no motive, the notes as I talked about yesterday, just lay out a timeline and that timeline was go to Mad Hatter's, drink, and, I will try to make that available as well. But there was no specific threat in it, there was nothing like that. So he just had the timeline, one of the interesting thing that we did find going back over the evidence today is as he did each thing, he actually scratch them off the list. So that was, and the list stops with pull fire alarm."

We don't know who he planned to target, but investigators say he was acting as a lone wolf. Officials at the University of Central Florida say they discovered this item that were ordered online and delivered to the campus, but Seevakumaran never picked them up from the mail room.

What was in the mail waiting for the deceased were two 22 round magazines that were designed for the GSG, weapon that he had, there was also a Black Hawk tactical sling designed to fit that particular weapon. And there was also a training DVD on proper shooting and use of lasers.