At least seven people died after a boat carrying migrants and refugees capsized five miles off the Italian island of Lampedusa, officials said.
About 10 other people were missing after the incident early on Wednesday, said Luigi Patronaggio, chief prosecutor of a team leading investigations into the deaths.
Among the dead included a pregnant woman.
The refugees are believed to have started their journey in Tunisia, said Patronaggio, who is working with magistrates in the Sicilian city of Agrigento.
Lampedusa’s mayor, Toto Martello, said: “This latest tragedy in the Mediterranean is heartbreaking, I wonder what else has to happen to make Italy and Europe understand that we cannot go on like this.”
Two coast guard ships had responded to a distress call from the boat, Italy’s coast guard said in a statement.
As the rescuers neared, the passengers “suddenly shifted” their positions, likely causing the boat to flip, the statement said.
Coast guard units rescued about 46 people from the eight-metre-long vessel after it overturned, and brought them back to Lampedusa, officials said.
More than 250 other people landed on the tiny island overnight on four ships, local media reported.
Arrivals in Italy had been falling in recent years, but numbers picked up again in 2021.
Nearly 20,000 migrants and refugees have arrived since the beginning of the year, many fleeing conflict and poverty in Africa and the Middle East.
That compares with just over 6,700 in the same period last year, interior ministry figures show.