An unidentified NYPD narcotics officer had one of his legs amputated below the calf last night after getting pinned by a car that jumped the curb during an accident in Brooklyn. The plainclothes officer, a five and a half year NYPD veteran, was loading drug bust prisoners into a van at about 5 p.m. at the intersection of Avenue U and East 34th Street in Marine Park, when two vehicles traveling opposite directions slammed into each other and jumped the curb. The cop was rushed to Kings County Hospital and is listed in serious but stable condition. No one else was hurt in the incident, and according to 1010 WINS, neither of the drivers have been charged and police have ruled this an accident.