This is CNN Breaking News.
Good morning, everyone.
I'm Audie Cornish, and we are following breaking news on this Tuesday morning.
A possible motive in the murder of four people in a Midtown Manhattan mass shooting,
the NFL headquarters are at the center of the investigation.
The gunman, identified as 27-year-old Shane Tamura of Las Vegas,
walked into a Park Avenue high-rise with an M4 assault-style rifle and opened fire.
That building is home to the corporate offices of the NFL,
a law enforcement source telling CNN the shooter had grievances with the league.
A source tells us a suicide note was found on his body and the shooter wrote he was suffering from CTE,
a brain disease linked to head trauma which can be caused by contact sports.
You can only be diagnosed with it after death and the suspect died of a self-inflicted wound.
According to our law enforcement partners in Las Vegas Mr. Tamora has a documented mental health history.
His motives are still under investigation and we are working to understand why he targeted this particular location.
A three and a half year NYPD veteran was shot in the back and killed by the suspect.
He was saving lives.
He was protecting New Yorkers.
He's an immigrant from Bangladesh and he loved this city.
And everyone we spoke with stated he was in person of faith.
According to an internal memo, one league employee was seriously injured in the attack.