TUNIS, Tunisia (AP) — At least 24 migrants trying to make their way to Europe died over two days when their fragile, overloaded boats sank, the prosecutor’s office of the coastal port city of Sfax said Saturday.

The Tunisian Coast Guard pulled the bodies of four sub-Saharan migrants from the waters off the coast of Sfax on Saturday, while 36 migrants were saved and three others were missing, according to Faouzi Masmoudi, spokesman for the prosecutor’s office in Sfax. A day earlier, 20 sub-Saharan migrants drowned when their boat went under about 35 miles (about 56 kilometres) from Sfax, and 17 others, including three children, were saved, Masmoudi said. He added that two of the survivors pulled from the water were reported in critical condition.

The numbers of migrants launching from Tunisian coastal waters and aiming to reach the shores of Italy have skyrocketed this year. The Coast Guard intercepted numerous other boats loaded with migrants on Friday and Saturday, Masmoudi said.

According to the Tunisian Forum for Economic and Social Rights, 132 migrants have died or disappeared in the first three months of this year while trying to reach Europe, reflecting the numbers of attempted and successful crossings.

Nearly two weeks ago, the Coast Guard recovered the bodies of 29 migrants in several boat sinkings.

The prosecutor’s office in Sfax, one of the main regions for migrants to launch their perilous expeditions, is trying to find those who provide desperate migrants with small unseaworthy vessels to make voyages onward to Europe.

People fleeing conflict or poverty routinely take boats from Tunisian shores toward Europe, even though the central Mediterranean is the most dangerous migration route in the world, according to the International Organization for Migration. Many migrants are from sub-Saharan Africa.