UPDATE:
The suspect is in custody; other than the suspect, four injuries have been reported, all non life-threatening.
The explosion occurred in the walkway connecting the Times Square subway station and Port Authority bus terminal. Police are investigating the possibility that the suspect planned to detonate a homemade pipe bomb that he had strapped to his body, which may have malfunctioned and exploded prematurely, according to this report from CNN:
Preliminary information, according to two law enforcement sources, one local and one federal, indicates a pipe bomb may have unintentionally exploded.
A man wearing a homemade device attempted to detonate it, and it either malfunctioned or did not go off the way it was supposed to, according to one NYPD source.
NPR reports:
New York police are responding to “reports of an explosion of unknown origin” in midtown Manhattan, at a location one block west of Times Square.
Shortly before 8 a.m. ET, police said a blast was reported at 42nd Street and 8th Avenue, location of the the Port Authority bus and subway station. The NYPD say that in the city’s subway system, “The A, C and E line are being evacuated at this time.”
One person is in custody, according to two NYPD sources with direct knowledge of the situation.