Police have concluded that a 19-year-old University of Texas student who killed himself after going on a shooting rampage at the Austin campus never meant to harm anyone.

UT Police Chief Robert Dahlstrom on Thursday said the student, Colton Tooley, waved at a guard and even said "excuse me" when he bumped into a person on his way into a library where he shot himself on Sept. 28.

Police say Tooley fired 11 rounds from an AK-47 that his father legally purchased. The teen fired into the ground and air, but passed up multiple opportunities to kill innocent bystanders and nobody was hurt.

Authorities say there were signs Tooley was depressed, but they have established no motive in the crime.