SANTA BARBARA, CA (KEYT/CNN) - Authorities say Elliot Rodger stabbed three men to death before going on a shooting rampage Friday night.
He killed six people and injured 13 others before turning the gun on himself.
Investigators and the Santa Barbara community are trying to make sense of why the 22-year-old went on a violent rampage.
Authorities say he stabbed the three in his apartment complex before going on a shooting spree across Isla Vista, where he lived and attended college.
Officials identified 10 locations where Rodger wreaked havoc.
He was carrying three semi-automatic handguns, all of which he obtained legally.
"We determined the suspect had over 400 remaining rounds of ammunition in his possession," said Santa Barbara County Sheriff Bill Brown.
A surveillance video shows people crouching in fear as gunfire goes off.
Authorities are still trying to figure out Rodger's motive, but after reading his manifesto, they believe mental illness played a large part.
Investigators are also looking at several YouTube videos posted by Rodger, one titled Retribution.
In it, Rodger goes on a rant about women ignoring and rejecting him.
Witness Kyle Sullivan described a grisly scene outside a sorority house where he found three girls shot.
"I could just tell immediately she was gone," he said. "I saw a gunshot wound to her abdomen, on her side, and one to her head."
Parents of those killed can only grieve.
The father of 20-year-old victim Christopher Martinez broke down.
"Why did Chris die?" Richard Martinez said. "Because of craven, irresponsible politicians and the NRA. They talk about gun rights, but what about Chris' right to live?"
This wasn't the first time Rodger was involved with the police.
Authorities say they documented three other times when they dealt with him over various issues - none leading to an arrest.
However, one time was for a welfare check after his parents were concerned about his mental state.
Police determined he was fine and didn't think he met the criteria for an involuntary hold.
Copyright 2014 KEYT via CNN. All rights reserved.