Unfortunately, as others have pointed out, an 8 day ban means that this is at least your 5th offense.
While the last incident leading up to this may have been an unfortunate accident, we can't overlook the other 4 times you have been banned for TKing. We want you to be able to have fun in rainbow and enjoy your time there, but we also want others to have fun too - and teamkilling is not part of our definition of fun. So once your ban period is over, please take this as a lesson learned and be much, much more careful in the future not to TK anymore.
While the last incident leading up to this may have been an unfortunate accident, we can't overlook the other 4 times you have been banned for TKing. We want you to be able to have fun in rainbow and enjoy your time there, but we also want others to have fun too - and teamkilling is not part of our definition of fun. So once your ban period is over, please take this as a lesson learned and be much, much more careful in the future not to TK anymore.