Exclusive-New York gunman was flagged by security camera system before attack, sources say

WASHINGTON/NEW YORK (Reuters) -Cameras at 345 Park Avenue flagged an approaching gunman on Monday as a potential threat that required immediate attention, seconds before he burst into the office skyscraper's lobby and began firing, according to two former federal officials familiar with New York building security systems. A computer-generated bright yellow box around him in the image indicates the use of software that analyzes live video feeds for threats requiring instant action, the former fed