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

Blackstone employees struggled on Tuesday to come to terms with the death of Wesley LePatner, one of the investment firm's senior executives who was gunned down late on Monday as she was leaving her Midtown Manhattan office.

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.