Police have named the suspect in the New York explosion as 27-year-old Akayed Ullah.
Four people have been left injured after a bomb exploded on a Manhattan subway platform.
The city's police force said the "explosion" was of "unknown origin" and was located near the Port Authority bus terminal on 42nd street and 8th avenue.
Asked if Mr Ullah had ties to Isis, Police Commissioner James O'Neill said the alleged attacker had made statements but refused to say what they were. Mr O'Neill said the young man had been taken to Bellevue Hospital with burns and other wounds.
Police sources told CBS News the suspected bomber has lived in the US for seven years and was of Bangladeshi origin.
Investigators are looking into the alleged attacker's residence and personal life at this time. Surveillance video of the incident is being reviewed.
New York City police say a man had an explosive device strapped on when it went off while he was in the subway.
It was a pipe bomb, attached by velcro and zip ties, but FBI bomb technicians and police officers are looking into it further.
The device exploded at the Times Square and Port Authority station on New York's west side - which is one of the city's most hectic commuter centres - at 7.30am in the midst of the morning rush.
Port Authority serves more than 65 million passengers a year and is the largest bus terminal in the US.
At least four people are said to have suffered non-life threatening injuries such as ringing in ears, headaches, and scrapes, according to police officials.
White House Press Secretary Sarah Sanders said President Donald Trump "has been briefed on the explosion in New York City".
The New York Mayor's Office said Mayor Bill de Blasio had also been briefed, saying police and fire crews were on the scene.
The incident took place less than two months after Uzbek immigrant Sayfullo Saipov killed eight people and injured eleven others by driving a rental truck down a New York City bike path close to the World Trade Center memorial before being shot by police.
