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

A shooting Monday at an office building in New York City that is home to the Blackstone investment firm and the NFL left four people dead, including an NYPD officer.

Bankers and traders returned to work on a somber Tuesday morning in Midtown Manhattan, New York's financial epicenter, one day after a shooting that killed four people, including a senior Blackstone executive.