Mayor Bill de Blasio said at a news conference at the scene of the explosion that it was an "intentional act", but not connected to terrorism, as far as initial indications go.

The Mayor made sure to emphasize, however, that the investigation into the incident is only in its preliminary stages, and that additional information is expected.

Widespread shutdowns were conducted by the NYPD in the aftermath of the explosion, and what appears to be a second explosive device was found.

A pressure cooker with wires attached to it was located four blocks away from where the explosion occurred.

Mayor de Blasio said that the injuries caused by the blast were "significant" but that none of them were life-threatening, as of yet.

One city official told the New York Times on condition of anonymity that the explosion likely came from an improvised device. "We don’t understand the target or the significance of it. It’s by a pile of Dumpsters on a random sidewalk," the official added.