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