NEW YORK -- A 27-year-old man wearing body armor and carrying an M4 assault rifle shot and killed four people, including off-duty New York Police Department Officer Didarul Islam, who was working security in a Midtown Manhattan office building, officials said during a press conference Monday evening.

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

As more information comes out about the man who shot and killed four people inside a midtown Manhattan office building before turning the gun on himself, there is a question of whether he should have been allowed to keep his concealed carry permit.