An active shooter incident occurred in Midtown Manhattan, New York, officials said. Here's what to know about 345 Park Ave.

Investigators are combing through evidence in the wake of New York City’s deadliest mass shooting since 2000, trying to figure out more about the gunman who unleashed an assault-style rifle in Midtown,

Officials said the gunman fatally shot himself after his attack, which set off a chaotic scene that rippled out into the heart of Manhattan during rush hour.