NEW YORK, March 6: The famous landmark area of Times Square was shut down early on Thursday morning for three hours after an explosive device was hurled at an army recruitment centre located in the middle of the square.

New York police were investigating the explosion which, officials said, was result of a small canister filled with gun powder thrown at the recruitment centre by a bicycle-riding person. No one was hurt.

The recruiting station -- the third that has stood on the site since 1946 -- has been the site of regular anti-war protests since the start of the Iraq war in 2003. Police officers said the explosion blew a hole through the front door of the recruiting centre, which is at the northern end of the structure.

Police are trying to identify the persons with the help of dozens of closed-circuit cameras in the area.

Witnesses told a local TV that they heard a big bang from their hotel rooms.

There were no reports of serious damage or injuries. The subway and bus service in the area was stopped temporarily.

“I was on the 44th floor and I heard it. I can feel it from up there,” a woman told WABC-TV.

“I heard a boom and thought it was a garbage truck,” said a maintenance-security worker at 570 Seventh Avenue. “I stayed in the building because I didn’t know what it was. I came out later and I was looking at the street and no cars are coming by. I saw all the helicopters,” he added.

In Washington, a spokesperson for the United States Department of Homeland Security said it was monitoring and investigating the explosion, Reuters reported.

Asked if there was a link to terrorism, the spokesperson said: “At this time we’re still investigating.”

AFP adds: The White House said the explosion “doesn’t appear to be terrorism,” adding that it was closely following the investigation.

Police Commissioner Ray Kelly said the blast was the result of an improvised explosive device that could have caused serious injury or even proved fatal.

“This was not a particularly sophisticated device, it was a low-order explosive in an ammunition box readily available in military surplus stores,” he told reporters from the scene of the explosion.