What happened under the tree on the night that bob ewell was killed?

On the night of the play jem and scout were on their way home when they were attacked from behind. mr. ewell grabbed jem and pushed scout over. he fought with jem, eventually breaking his arm and knocking him out. then he grabbed scout. if she hadnt had on her ham costume she would have been strangled to death. all of a sudden mr. ewell lets go of scout and starts to fight someone else. turns out boo has come to save them. he stabs mr, ewell with a kitchen knife and then carries jem home. after scout gets up she runs home to.