EMPLOYEE ATTEMPTED TO CLOSE REAR DOOR. SHE WAS WEARING A HARNESS AND EXTENSION. AT THAT TIME SHE TRIED TO UNHOOK HERSELF BUT WAS UNABLE TO DO SO AND PANICKED. SHE CALLED FOR HELP, BUT INAME WA S UNABLE TO UNHOOK IT, SO SHE COULD NOT PROCEED TO NEXT CAR AND INSTEAD FELL BETWEEN CARS (DANGLING) UNTIL INAME WAS FINALLY ABLE TO DISCONNECT HER.