An 18-year-old man was killed Thursday when he jumped from a moving car behind the East Falmouth Library, Falmouth police said. Albino Fernandes jumped out of the moving car in which he was a passenger at about 9:35 a.m., police said. Police said it was unclear how fast the car was traveling. An officer was in the area and immediately rendered assistance, while summoning the Falmouth Fire and Rescue Department. Fernandes was taken to the Falmouth Hospital emergency room, where he was later pronounced dead. “The circumstances which led to this tragic event are currently under investigation,’’ police said.