On an ominous Friday the 13th evening, Bronx teenager David Ellis was riding his bike north up Webster Avenue when he was struck from behind by Nissan Maxima near East Gun Hill Road, according to police. After being hit, Ellis, 18, was thrown into the southbound lane on Webster and hit again, this time by an oncoming Ford Explorer. While the Maxima fled, police said the driver of the Explorer stopped and waited while emergency workers made their way to the scene. Ellis was taken to Montefiore Medical Center, but was pronounced dead on arrival. No arrests have been made, but police are continuing to investigate the incident. Ellis lived on Marion Avenue just north of Fordham Road.