Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday.

Four people were killed, including an off-duty New York City police officer, when a gunman opened fire in an office tower before fatally shooting himself, officials said.

Rep. Nicole Malliotakis spoke with Fox News Digital after the deadly shooting that left multiple people including a police officer dead.

A note written by the shooting suspect was found at the midtown Manhattan office building scene where he killed four people, including an NYPD officer, and himself a day ago, officials familiar with the investigation said overnight.

The 27-year-old Nevada man opened fire at a New York City office building, killing at least four people and then himself.

A frequent Fox News guest, who touts himself as a law enforcement expert due to his brief tenure with the New York Police Department, groused that “bystander apathy” led to the deaths of four people in a deadly Manhattan shooting Monday, urging citizens to “deputize” themselves and confront gun-wielding suspects.

Shane Tamura, the suspect in the deadly shooting in Midtown Manhattan, carried a note in his pocket claiming he suffered from CTE and also made references to the NFL, police sources told ABC News.