City of El Cajon, San Diego County Gillispie Air field.  El Cajon Fire department personal worked to extricate two victims of a  plane crash short of the runway.  According to witness the plane was too low and clipped a security fence then cart wheeled to rest short of the normal runway.  Fire department personal said both the unidentified persons were transported to trauma hospitals, one by ground ambulance and one by helicopter. The cause of the crash is under investigation by the El Cajon Police and the NTSB.