Kill Blocking Session

SELECT 'alter system kill session ''||ss.sid||','||ss.serial#||'';'
FROM v$process pr, v$session ss, v$sqlarea sqa
WHERE pr.addr=ss.paddr
AND ss.username is not null
AND ss.sql_address=sqa.address(+)
AND ss.sql_hash_value=sqa.hash_value(+)
AND ss.status='ACTIVE'
AND ss.blocking_session_status='VALID';