Officials have blamed the Tunisian captain of a fishing boat for causing the deaths of hundreds of migrants. They say the migrants were locked inside when their boat overturned in the Mediterranean Sea over the weekend.

Prosecutors said on Tuesday that 27-year-old Mohammed Ali Malek was arrested on suspicion of killing many people. The prosecutors said the captain mistakenly turned his overloaded boat into a merchant ship that was coming to its rescue.

Only 28 survivors have been brought to Italy from the hundreds of Bangladeshi migrants on board the boat. Most of the migrants were African and Bangladeshi. Police have said as many as 950 people may have died. It appears to be the worst disaster ever among migrants fleeing across the Mediterranean Sea to Europe.

The lead prosecutor said so few people survived because most of the migrants on board had been locked in the lower levels of the fishing boat. Many of the passengers were women and children.