Complex sentence: Graham arrives to the scene quickly with the reinforcments, and kills the ant attacking Peterson, but rushes over to Peterson's side with only enough time to hear Peterson's last words confirming that the boys made it to safety, before Peterson dies in his arms.
Split into simpler sentences: Graham arrives to the scene quickly with the reinforcments, and kills the ant attacking Peterson. He rushes over to Peterson's side just in time to hear Peterson's last words confirming that the boys made it to safety, before Peterson dies in his arms.