Updated 6:30 p.m. ET
ORLANDO, Fla. The student behind a foiled attack plot at a Florida university was working off a checklist that included plans to get drunk, pull a fire alarm and then "give them hell," authorities said Tuesday.
James Oliver Seevakumaran was crossing items off his list ahead of his planned attack his classmates with guns and homemade explosives, University of Central Florida Police Chief Richard Beary said at a news conference.
The list found along with his dead body early Monday included drinking at a bar near campus and pulling the fire alarm - which investigators believe was meant to flush out victims. Beary says the final item was "give them hell."
Instead, Seevakumaran shot and killed himself as police officers arrived in response to the fire alarm and a 911 call from a roommate. Beary says authorities confirmed he went to the bar and drank.
At the time of the attack, packages were waiting for Seevakumaran at a campus mailroom containing two 22-round magazines and a sling for his rifle and a firearms training DVD.
Beary said authorities still aren't aware of a motive or significant circumstance that led Seevakumaran to plan for an attack. The chief said no written explanation was left.
Seevakumaran was described as a loner both by police and in a brief statement from his family released Tuesday.
One of his dorm mates said he recalled friendly but distant interactions with James Oliver Seevakumaran, while several others approached by a reporter said they didn't recall seeing or interacting with him. A roommate interviewed by a campus media outlet said Seevakumaran was an introvert who never had visitors.
On Tuesday, police tape and squad cars were gone outside the dormitory where police say the Seevakumaran had armed himself early Monday with two guns, hundreds of rounds of ammunition, a backpack filled with explosives.
Seevakumaran's plans were thrown off by campus police officers' quick response to the fire alarm and a 911 call from his roommate, who hid after Seevakumaran pointed a gun at him, UCF Police Chief Richard Beary said.
Roommate Arabo Babakhani, 24, said he ran into his room and slammed the door on his roommate after seeing the gun and hid behind furniture before calling 911.
Babakhani told CBS News correspondent Mark Strassman that Seevakumaran avoided eye contact and always acted very distant.
"If you said anything to him or walked by him or anything, he would just ignore you," Babakhani said. "He would stare off into the distance and pretend like you never existed. He only made eye contact with me when he pulled the gun on me."
Seevakumaran's family also said he was a loner who didn't have a history of violence in a brief statement released by authorities. AP reporters have also knocked on the doors of his mother and sister's homes, but no one answered.
"The family of James Oliver Seevakumaran states that James was a loner and did not have a history of violence. The family does not wish to make any further comments to the media and has requested privacy," said the statement, which Beary read at a Tuesday afternoon press conference.
Freshman mechanical engineer student Spencer Renfrow said when he would see Seevakumaran in the dorm's hallways and elevator, he would wave and Seevakumaran would wave back.
"Everything would seem fine," Renfrow said.