CCTV footage has shown the moment a terror suspect's bomb went off at one of New York's busiest commuter hubs.
The explosion, which rocked the Port Authority Bus Terminal during the morning rush, hour was "an attempted terrorist attack", the city's mayor says.
It's believed the suspect, who was arrested at the scene, had a pipe bomb strapped to his body which exploded in a passageway underground.
The NYPD police commissioner identified the suspect as Akayed Ullah, 27.
The fire department tweeted there were four injuries, all non-life threatening.
One of the injured was a Port Authority police officer.
The fire commissioner said Ullah suffered burns and lacerations in the explosion. Three other people nearby suffered minor injuries.
Police were not yet identifying the device used. Local television channel WABC cited police sources as saying a possible pipe bomb detonated in a passageway below ground and WPIX cited sources as saying a man with a "possible second device" has been detained in the subway tunnel.
Mayor Bill de Blasio later said there were no known other incidents and the suspect believed to have acted alone
The bus terminal was temporarily closed, the Port Authority of New York and New Jersey said in a Twitter statement.
A large swathe of midtown Manhattan was closed to traffic, between 45th Street to 40th Street and 7th Avenue to 9th Avenue, police said. Subway trains were bypassing the Times Square station, the city's busiest.
"There was a stampede up the stairs to get out," said Diego Fernandez, one of the commuters at Port Authority. "Everybody was scared and running and shouting."
President Donald Trump has been briefed on the incident. New York governor Andrew Cuomo was on the scene.
WABC reported the suspect was from Bangladesh, and that he has been in the US for seven years and has an address in New York's Brooklyn.
First reports of the incident began soon after 7am local time, at the start of the city's rush hour. New York in December sees a surge of visitors who come to see elaborate store displays, the Rockefeller Center Christmas tree and Broadway shows.