Complex sentence: On the final lap of the Nationwide Series event, Brad Keselowski attempted to pass leader Regan Smith, who had moved to block and a chain reaction ensued with Kyle Larson's car flying into the protective fencing.
Split into simpler sentences: On the final lap of the Nationwide Series event, Brad Keselowski attempted to pass leader Regan Smith. Smith had moved to block and a chain reaction ensued with Kyle Larson's car flying into the protective fencing.