Turkish security forces have raided a hijacked passenger ferry and killed the lone assailant, ending a 12-hour siege on the boat in the country's northwest, officials say.<br /><br />The commandos killed the man who hijacked the ferry with about 20 passengers on board, Huseyin Avni Mutlu, Istanbul's governor, announced on Saturday.<br /><br />Al Jazeera's Anita McNaught reports from Istanbul.