A Bronx teen who was found by his father gunned down in a park was likely killed by a stray bullet fired from a different location — a “one-in-a-million” shot, police sources said yesterday.

Kemar Bryan Brooks, 14, was struck in the back of his head and found about 6 a.m. on Friday in Haffen Park, cops said.

Detectives now believe he was hit by shots fired two blocks away.