New York City Mayor Mike Bloomberg on Thursday condemned the early morning bomb attack that lightly damaged the US Army recruitment centre at Times Square calling it "a cowardly act," according to dpa. The blast at 4 am was caused by a small explosive device that was thrown into the building on the street level in the middle of Times Square, a must-see place for tourists to the city. Police reported no injuries, and only a few windows were broken. "The attack was deliberately directed at the recruiting centre and that is an insult to the efforts of the country's servicemen and women," Bloomberg said in a press conference, urging New Yorkers not to be intimidated by the attack. "The city is back and open for business," and the traffic has returned to Times Square, the mayor said. Local news reports said New York Police Commissioner Ray Kelly said the city's arson and explosion unit was examining the device, which was described as unsophisticated, but could have been deadly. Police closed traffic around the centre at 7th Avenue and Broadway after the attack, but reopened it during the morning rush hour. Reports said cameras around the centre showed a man riding a bicycle fleeing after the attack. Police were investigating the source of the attack.