Last Updated Apr 4, 2018 6:57 PM EDT
SAN FRANCISCO -- Police in San Bruno, California, said it was a beef with YouTube that drove a 39-year-old woman to-- apparently at random -- Tuesday. She then turned the gun on herself. Details about the suspect have since come to light.
Online the shooter, Nasim Najafi Aghdam, had already expressed her anger at YouTube.
"I am being discriminated and filtered on YouTube. My new videos hardly get views," she was heard saying on one of her uploaded videos.
She had been a prolific contributor to the video sharing site, posting videos on fitness, veganism and animal rights.
Police say Aghdam legally owned theshe used and visited a shooting range Tuesday morning before going to YouTube's headquarters.
Police said the shooter wounded three people in YouTube's open courtyard and then killed herself.
Investigators covered her body with a yellow tarp.
"Well, we know that she was upset with YouTube, and right now that's the motivation that we've identified," San Bruno Police Chief Ed Barberini said.
Last week, Aghdam's family reported her missing from her home in San Diego. Then Tuesday morning, hours before the shooting, police in Mountain View found her sleeping in her car, about 25 miles south of the YouTube campus. After interviewing her for 20 minutes, authorities alerted her family.
Aghdam's father says he warned officers, but in a statement the police said: "At no point did her father or brother mention anything about potential acts of violence."
Investigators visited family homes in Southern California on Wednesday. At her father's house, one relative said Aghdam came from Iran as a refugee at 18, about 21 years ago.
"How come, for getting stupid gun, we don't need mental doctor?" one family member said. "I don't know."
YouTube has not responded to CBS News' request for information about Aghdamn's history with the company and whether any of her videos were blocked.
Barberini confirmed Wednesday they found no links between Aghdam and any of the victims. Two women wounded in the attack were released Wednesday from a San Francisco hospital. The third victim, a 36-year-old man, was upgraded from critical to serious condition.
Officials are serving search warrants at two houses in Southern California associated with Aghdam, reviewing surveillance video and scouring her social media posts, Barberini said.
San Bruno is "no stranger to a crisis," said Mayor Rico Medina, and praised first responders who "ran into an active shooting situation as it occurred."
"No one goes to work thinking this is what will happen to them around their meal time, but it did," Medina said.