Four people were killed and a fifth was injured in a mass shooting at a Midtown Manhattan office building on Monday. The injured victim was an employee at the NFL, according to NFL Commissioner Roger Goodell. Here's what we know about the four people killed:

Blackstone told employees on Friday it will reopen its New York headquarters on August 4, a week after shuttering it in the wake of a shooting that killed four people including one of its executives.

Workers in business attire were seen piling couches up against their office door -- with the towering furniture reaching the ceiling.