The Tanzanian island of Zanzibar has begun three days of official mourning for more than 200 people who were killed when an overloaded ferry sank on Friday night. The authorities say many others are still unaccounted for. More than 600 people were rescued. Friends and relatives are still identifying the dead. They have been taken to a football ground in the centre of Zanzibar and placed in separate rows of men, women and children. Survivors said the ferry was extremely overloaded.