WHILE SETTING BLOCKS INTO POSITION WITH CRANE, THE BLOCK BEGAN TO SWING AWAY. THE EE TRIED TO STOP THE BLOCK AND INJURED HIS LOWER BACK. THE EE CONTINUED TO WORK AND REPORTED THE INJURY ON 10- 2-03 TO THE SUPERINTENDENT. THE EE WAS SENT TO THE DOCTOR ON 10-03-03 AND RETURNED TO WORK.