ANKARA, Turkey (AP) – Spanish police say they have arrested 17 members of an alleged human trafficking network that threatened Moroccan migrants who sought a refund when attempts to reach Europe by sea failed.

The National Police said Tuesday the busted cell operated from Ceuta, a tiny Spanish enclave in northern Africa.

The alleged traffickers charged between 1,500 and 4,000 euros ($1,700 to $4,500) for taking the Moroccan migrants across the Straits of Gibraltar in high-speed rubber boats. According to police, a hitman threatened the migrants who dared to ask for a refund if they failed to complete the trip.

More than 5,500 migrants have reached Spanish shores this year and 121 have died trying to, according to the International Organization for Migration. Last year, a record 57,000 arrived and more than 800 died.