Coast guard divers found the wreck late on Thursday on the sea floor, 130 feet (40 meters) below the surface, with bodies scattered around it.
“Today the operations we plan to do are focused on searching inside the ship where bodies are trapped,” Capt. Filippo Marini, a coast guard spokesman, told reporters on Friday. “We don't have the number of the bodies; we don't know the real number yet.”
Rescue crews hauled body bags by the dozens into Lampedusa port on Thursday, lining them up under multicolored tarps on the docks.
The UNHCR believes this is likely to be the biggest such tragedy on record involving migrants in the Mediterranean.