See Photos from the Aftermath of the Chelsea Explosion

Crime scene investigators at the scene of an explosion in Manhattan's Chelsea neighborhood in New York on Sept. 18, 2016.

New York Gov. Andrew Cuomo, right, walks from the scene of an explosion in Manhattan's Chelsea neighborhood in New York on Sept. 18, 2016.

Mayor Bill de Blasio, center, and NYPD Chief of Department James O'Neill, left, react during a press conference near the scene of an explosion on West 23rd street in Manhattan's Chelsea neighborhood in New York on Sept. 17, 2016.

Firefighters arrive at the scene of an apparent explosion in Manhattan's Chelsea neighborhood in New York on Sept. 17, 2016.

A fire truck is seen near a blocked off road near the site of an alleged bomb explosion on West 23rd Street in New York on Sept. 17, 2016.

People try to access the area near the scene of an explosion on West 23rd Street and 6th Avenue in Manhattan's Chelsea neighborhood, in New York, early Sunday, Sept. 18, 2016. An explosion rocked the block of West 23rd Street between Sixth and Seventh Avenues at 8:30 p.m. Saturday. Officials said more than two dozen people were injured. Most of the injuries were minor. (AP Photo/Andres Kudacki)

Police officers look for suspicious packages along Fifth Avenue near the scene of an explosion on West 23rd Street and 6th Avenue in Manhattan's Chelsea neighborhood in New York in the early hours of Sept. 18, 2016.

Onlookers stand behind a police cordon near the site of an explosion in the Chelsea neighborhood of Manhattan, New York, on September 17, 2016.

Police stand guard near the scene of an explosion in Manhattan's Chelsea neighborhood, in New York, Saturday, Sept. 17, 2016.