NEW YORK — Investigators on Wednesday said they believed YouTube’s policies motivated a woman who shot three people at YouTubes headquarters in San Bruno, Calif., before killing herself.

The attacker, identified as Nasim Najafi Aghdam, had been seen at a nearby shooting range before the attack, and a gun registered in her name was found at the scene.

Aghdam, who was in her late 30s and had lived in Southern California, often discussed Persian culture, veganism and animal cruelty; performed music parodies; and gave exercise tutorials on YouTube and on her personal website.

In Iran, Aghdam was known as “Green Nasim,’’ a social media star with followings on YouTube, Instagram, and elsewhere who was sometimes admired, sometimes mocked.

Aghdam had YouTube pages in Persian, Turkish, and English. In several videos, she stated she had been born in Iran. She explained she and her family are members of the Baha’i faith, a persecuted minority in majority Muslim Iran.

In Iran, she had tens of thousands of followers on social media. Several of her colorful — and sometimes bizarre — videos had gone viral.

Life in the United States had not been good, she said in a video posted last week. “There they kill you by ax,’’ she said of Iran. “Here they kill you with cotton’’ — an Iranian expression meaning to die by something that you do not know is dangerous.

In another video, she responded to viewers who had begun to wonder if she was mentally ill: “I don’t have any special mental or physical disease, but I live on a planet filled with disease, disorders, perversions and injustices.’’

Aghdam fired “multiple shots’’ from a Smith & Wesson 9mm semi-automatic handgun, which was registered to her, Ed Barberini, chief of the San Bruno Police Department, said Wednesday. The gun was recovered at the scene.

There is no evidence linking Aghdam to any of the shooting victims, Barberini said.

On Tuesday morning, before driving to the YouTube offices, Aghdam visited a local gun range, police said. Investigators were searching two homes in Southern California associated with the suspect. She parked at a business near YouTube. She entered one of the company’s garages and then walked into an outdoor courtyard where employees were eating lunch.

“It is believed that the suspect was upset at the policies and practices of YouTube. This appears to be the motive for this incident,’’ Barberini said.

The three victims were taken to Zuckerberg San Francisco General Hospital. Two women, a 32-year-old who was admitted in serious condition and a 27-year-old who was admitted in fair condition, were released late Tuesday, a hospital spokesman said. The third victim, a 36-year-old man, had improved from critical to serious condition.

Police in Mountain View said they found Aghdam sleeping in a car at 1:40 a.m. Tuesday. The vehicle was tied to a person reported missing March 31. Aghdam told police she was not a danger to herself or others. “At no point during our roughly 20-minute interaction with her did she mention anything about YouTube . . . or that she had planned to harm herself or others,’’ police said.