What’s the name of this movie? Tell me please!

I was looking for the movie I can’t remember any specific name of actor, actress, year but Hollywood movie for sure. The movie’s story is similar to movie Leon but with a boy.The story as I remember is an assassin guy needed shoot a boy front of a car who was target’s family but he could not kill the boy because the boy looked too innocent. After he was taking care the boy and the boy become assassin like him.