Officials say at least 107 people were killed when an overloaded ferry sank near Zanzibar off the coast of Tanzania.

State minister Mohammed Aboud says the ferry was carrying 600 people Saturday when it capsized and sank between Zanzibar and Pemba Island. At least 250 people have been rescued, but hundreds of people are still missing.

A doctor told the Reuters news service bodies were arriving by the “truckload” and said he expected the death toll to rise.

Emergency responders are searching for survivors.