Blast at US army recruitment centre
New York mayor condemns attack on Times Square military office.
A woman in a nearby building heard a “huge bang” and came down to investigate but was kept back by police.
The building is on a traffic island between Broadway and Seventh Avenue in Times Square.
It has frequently been the focus of demonstrations against the US-led military action in Iraq and Afghanistan.
Captain Charley Jaquillard, who is in charge of US army recruiting in Manhattan and works in the centre, said nobody was in the building when the explosion occurred.
Police said the streets in the area would remain closed until the investigation was complete.
New York has been on a heightened state of alert since the attacks of September 11, 2001, when hijackers crashed two passenger jets into the World Trade Centre, killing nearly 3,000 people.