NEW YORK CITY -- Police in New York City are searching for a group of teenagers after one of them allegedly attacked an off-duty firefighter.The attack happened around 9:25 a.m. Saturday on E. 86th Street between 2nd and 3rd avenues in Manhattan.Police said the firefighter was trying to stop the teenagers from harassing an elderly couple.That's when, they said, one of the teens punched the firefighter in the back of the head. Police said the teen then stomped on him while he was down.The firefighter suffered a mild concussion to the head and five broken teeth.He was taken to the hospital where he needed 25 stitches. He has since been released.Police are searching for three females and three males, described between the ages of 15 and 17.