(CNN) -- By some accounts, University of Texas sophomore Colton Tooley was brilliant in mind and respectful always in his behavior to others.
His friends and family in Austin struggled Wednesday to come to terms with the tragedy that befell the teenager they knew after police identified him as the student who brandished an AK-47 assault rifle through campus and then turned the gun on himself.
No one else was injured in Tuesday's shooting incident. Police still do not know what Tooley's motives were.
His teachers at Crockett High School recalled Cooley, 19, as a bright, meticulous student who excelled in every subject, according to a statement from Craig Shapiro, principal of a school now dealing with the tragic deaths of two of its students. Another student, James Hinojosa, was killed in a train accident last week.
Shapiro said the Crockett High School community was shocked and saddened by Tuesday's tragedy.
"Our hearts go out to the family and friends of Colton Tooley," he said.
Colton graduated from Crockett in 2009. He was ranked seventh in his class.
"It doesn't make sense at all," said David Sepeda, Tooley's high school friend.
Sepeda told CNN affiliate KXAN that Tooley was shy but friendly.
"In high school, he was always nice. He was quiet, but he wasn't like threatening or malicious or creepy-looking," Sepeda said. "He would just walk around and mind his own business".
According to the university, Tooley began firing the AK-47 near the Littlefield Fountain about 8:10 a.m. Officers from the University of Texas Police Department and the Austin Police Department pursued Tooley, who went into the Perry-Castaneda Library.
CNN
