An explosion was heard in midtown Manhattan in New York City on Monday, New York police announced. It said that a number of people were injured in the blast, but has not yet determined the nature of the explosion. Local news channel WABC cited police sources as saying a possible pipe bomb detonated in a passageway below ground at Port Authority, one of the citys busiest commuter hubs, during Monday mornings rush hour. Media reported several people were injured, and WPIX television reported, citing sources, that a man with a “possible second device” has been detained in the subway tunnel. The blast led to delays along some of the subway lines that pass beneath the bus terminal. Some passengers have been evacuated as a precaution