Nicolini said the ship had caught fire after those on board set off flares so it would be seen by passing ships.
The ship apparently then capsized, spilling the passengers into the sea near Conigli island.
Lampedusa is closer to Africa than the Italian mainland—a mere 70 miles (113 kilometers) off the coast of Tunisia—and is the frequent destination for smugglers' boats.
Interior Minister Angelino Alfano canceled his appointments Thursday and headed to Italy's southernmost island to oversee the rescue operations.
Pope Francis, who visited Lampedusa in July, quickly sent condolences.
