Chelsea Explosion: Bomber at Large, NYC Mayor Reluctant to Call Terrorism

Police and firefighters work near the scene of an apparent explosion in Manhattan's Chelsea neighborhood, in New York, on Sept. 17, 2016. (AP Photo/Andres Kudacki)

Police Commissioner James O'Neill said he is concerned that a bomber is at large in the city, but also expressed confidence in the ability of police to find the culprit or culprits.

New York Governor Andrew Cuomo called the bombing an act of terrorism during Sunday press conference, but also said it doesn’t appear to be related to international terrorism, according to CNN.

Terrorism is defined as using violence or intimidation to achieve political, religious, or ideological goals.

New York Gov. Andrew Cuomo (R) walks through the scene of an explosion on W. 23rd Street in Manhattan's Chelsea neighborhood in New York, Sept. 18, 2016, after 29 passersby were injured Saturday night. (AP Photo/Craig Ruttle)

The NYPD as well as the State Police and National Guard boosted their presence in the city, the Mayor said.

Both federal and local law enforcement agencies, including the FBI, are involved in the investigation.

Subways and PATH trains renewed operation, but the E, F, and M subway trains skip the 23rd Street station and 1 trains skip the 23rd and 28th street stops.

Street closures in New York City as of noon Sunday, Sept. 18, 2016. (Courtesy NYPD)

Anyone with information is asked to call the NYPD tip line on: 1800-577 TIPS (8477).