Shane Tamura, suspected NYC gunman, was former Granada Hills Charter High football player

Shane Tamura left behind note after NYC shooting

Shane Tamura, the man accused of shooting and killing four people in midtown Manhattan, left a note behind that talks about CTE.

LOS ANGELES - Shane Tamura is suspected of killing four people, including a New York Police Department officer, Monday afternoon in Midtown Manhattan. 

The shooting took place at a skyscraper that is home to the headquarters of both the NFL and Blackstone, one of the world’s largest investment firms, as well as other tenants.

Authorities said Tamura fatally shot himself after carrying out the deadly attack. 

NYC mass shooting suspect has SoCal ties

Officials said the gunman in the New York shooting rampage has ties to Southern California.

A motive for the shooting is unknown. According to NYPD Police Commissioner Jessica Tisch, Tamura drove from Nevada to New York City and entered New York the day of the shooting.

Tisch said he has a history of mental illness and acted alone, though investigators aren't sure why he targeted 345 Park Avenue office building.

"I cannot speak for any prior law enforcement contact to have had. I cannot, other than to say that, our partners in Las Vegas made us aware of a mental health history. Just two weeks ago," Tisch said during the press conference.

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• Midtown Manhattan shooting leaves 4 dead, including NYPD officer

Shane Tamura, NYC gunman, had ties to Los Angeles

Shane Tamura, the suspected gunman who killed four in Midtown Manhattan, went to school and played football in Los Angeles' Granada Hills neighborhood.

Local perspective:

FOX 11 learned that Tamura, 27, played football at Granada Hills Charter High School. 

Walter Roby was head coach at Granada Hills during Tamura's senior year.

"Shane was very quiet. He was a quiet, hard worker. He was coachable. So whatever we asked him to do, he was doing it. He led by, you know, his actions on the field. He was our, you know, one of my top offensive players at the time," Roby told FOX 11's Matthew Seedorff. 

"Could I have done more? Could I help the kid? Could I have reached out to him or could you reach out to me? It's just a lot of things I'm trying to process right now."

Tamura also attended Golden Valley High School in Santa Clarita before attending Granada Hills. 

Shane recently worked as a security guard at a casino in Las Vegas.

Who is Shane Tamura? Suspect in Manhattan shooting

Police say Shane Tamura killed four people including an NYPD officer then took his own life on the 33rd floor of a real estate management company.

If you or a loved one is feeling distressed, call the National Suicide Prevention Lifeline. The crisis center provides free and confidential emotional support 24 hours a day, 7 days a week. Call or text 988 or chat at 988lifeline.org.