Workers returned to 345 Park Avenue​ under the watchful eyes of NYPD officers and a surplus of security after the NYC mass shooting.

Police officers in New York City responded to reports of an active shooter in a midtown Manhattan building that houses Blackstone investment firm and NFL headquarters.

Four people have been killed, including one NYPD officer, after gunfire erupted in Midtown Manhattan Monday afternoon, officials said. Here's a look at what happened in New York Monday evening. All time stamps are based on East Coast times. Four people were shot and killed in Midtown Manhattan on Monday.