No fewer than forty people, including infants, were killed when a boat conveying migrants seeking greener pasture to reach Europe sank off the coast of Tunisia, according to local judicial authorities. Around 30 others were rescued.

Mahdia court spokesman Walid Charbi said that Tunisian naval units that arrived on the scene on Wednesday, rescued 30 other migrants on board the boat, which sank off the Mediterranean port of Mahdia in central Tunisia.

Charbi said those aboard were from sub-Saharan Africa, without providing further details.

The prosecutor’s office has ordered an investigation to determine the causes and circumstances of the sinking, Charbi said.

Mahdia is Tunisia’s second-biggest port of call for departures of boats carrying people from Tunisia and elsewhere in Africa as well as Asia seeking to reach Europe.

Tunisian security forces have ramped up efforts to prevent migrants from reaching or crossing the sea a journey that can be deadly.