What we know about the NYC office tower shooting, victims and suspect Shane Devon Tamura

Five people, including a New York City police officer, died Monday in a Midtown shooting. Suspected gunman Shane Devon Tamura died of a self-inflicted gunshot wound, officials said.

A gunman opened fire inside a high-rise corporate building in the heart of Manhattan on Monday evening, killing a New York City police officer, a Blackstone executive and two other people, officials said.

The suspected shooter acted alone and died from a self-inflicted gunshot wound, law enforcement officials told NBC News.

Police officers and emergency vehicles respond to a shooting in midtown Manhattan on Monday.John Lamparski / AFP via Getty ImagesThe deadly gunfire, which was first reported about 6:30 p.m., was treated as an active shooting, prompting warnings and office evacuations, with lines of people seen leaving the building with their hands above their heads.

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The gunman’s motive has not been disclosed. Officials familiar with the investigation told NBC News, however, that the suspect left a note that mentions a possible cause of his mental illness.