NEW YORK — The gunman police believe has been targeting homeless men in New York City and Washington, D.C., shooting at least five of them as they slept and leaving two dead, was nabbed in the nation’s capital early Tuesday, authorities said. “Early this AM, law enforcement arrested the suspect in Washington, DC,” the Metropolitan Police Department said in a tweet. “He is currently being interviewed at our Homicide Branch. Additional information will be forthcoming. Thanks to the community for all your tips.” The NYPD confirmed the arrest and said more details would be known later in the morni…