De Blasio said the blast was "an intentional act" and tried to calm any fears among nervous New Yorkers, saying the explosion had no terrorist connection and wasn't related to a pipe bomb explosion earlier Saturday in New Jersey at a charity run.
A law enforcement official told the Associated Press that a second device that officers were investigating four blocks from the scene appeared to be a pressure cooker attached to wiring and a cellphone. The source, speaking on condition of anonymity because the person was not authorised to speak about an ongoing investigation, said the device was found inside a plastic bag on West 27th Street.
The law enforcement official also said that the explosion appears to have come from a construction toolbox in front of a building. New York officials said the incident was not due to a gas leak.