A boat crowded with 700 migrants overturned north of Libya on Saturday, leaving at least 24 confirmed dead and many missing. Italy’s Coast Guard stated that the migrants’ 20-meter vessel could have capsized as the people on board rushed to one side of the craft after seeing a Portuguese merchant vessel approach it.

Initial reports stated that 28 survivors had been rescued whereas Maltese Prime Minister Joseph Muscat put the number of survivors at 50 on Sunday. Muscat also said that the tragedy is the biggest human tragedy of the last few years.

Authorities state that there is no immediate way to determine how many people were on board. It is possible that many bodies will never be recovered. There is the suspicion that this has been the case in similar tragedies off the coasts of Libya, Italy and other areas around the Mediterranean in recent years.

Italian Prime Minister Matteo Renzi has called for an emergency meeting on immigration this week after the latest tragedy. He also summoned his top ministers to a Sunday meeting in Rome to discuss the tragedy

Last week, 400 people were presumed to have drowned when another boat capsized.