Didarul Islam, a 36-year-old NYPD officer, was off duty and working a security job when he was fatally shot by a gunman who opened fire at the 345 Park Avenue office building on Monday.

Four people have been killed, including one NYPD officer, after gunfire erupted in Midtown Manhattan Monday afternoon, officials said. Here's a look at what happened in New York Monday evening. All time stamps are based on East Coast times. Four people were shot and killed in Midtown Manhattan on Monday.