Complex sentence: While in a local diner, Callahan observes a bank robbery in progress and kills two of the robbers; he wounds a third (Albert Popwell), who ends up on the ground with a loaded shotgun nearby.
Split into simpler sentences: While in a local diner, Callahan observes a bank robbery in progress. He goes outside and kills two of the robbers; he also wounds a third (Albert Popwell), who ends up on the ground with a loaded shotgun nearby.