Firefighters and the police were responding to a report of an explosion in Manhattan on 23rd Street between Avenue of the Americas and Seventh Avenue on Saturday night, the authorities said. Information about the source of the explosion was not immediately available. The explosion was reported around 8:30 p.m.
As the authorities sought to identify what had caused the explosion, they described the second device as a pressure cooker resembling the one used in the deadly Boston Marathon bombings in 2013, according to a police official, who spoke on the condition of anonymity to discuss a continuing investigation.
It was unclear whether the blast on West 23rd Street had been caused by the same type of explosive.
In the immediate aftermath, the police shut down a swath of Manhattansouth of Midtown. The area from 14th Street to 32nd Street was closed to traffic between Fifth and Eighth Avenues. But by 7 a.m., only 23rd Street remained closed.
A grim Mr. de Blasio, speaking at a news conference at the scene around 11:15 p.m., said “injuries are significant.” But for the moment, he said, none of them were life-threatening.