In 2010, the NCNCA had several "bad" Cat 4 crashes that were discussed extensively on the NCNCA forum. One of the culprits was racers sprinting for deep in the money spots i.e. 30th place.
Here is the crash sequence from the 2010 Bariani Road Race finish. A rider in the front goes down with the Cat 4 field together at the finish sprinting - mayhem followed.
http://hcphoto.smugmug.com/DBC-and-N...Qm9qVPx/Medium