ROME (AP) -- At least 40 migrants died Saturday in the hold of an overcrowded smuggling boat in the Mediterranean Sea north of Libya, apparently killed by fuel fumes, and some 320 others on the same boat were saved by the Italian navy, the rescue ship's commander said. Migrants by the tens of thousands are braving the perilous journey across the Mediterranean this year, hoping to reach Europe and be granted asylum. They are fleeing war, persecution and poverty in the Middle East, Africa and Asia. "The dead were found in the hold," Cmdr. Massimo Tosi, speaking from the navy ship Cigala Fulgosi while the rescue was still ongoing. Asked by RaiNews24 how the migrants died, Tosi said "it appears to be from inhaling exhaust fumes." "They are still counting the victims," Interior Minister Angelino Alfano told reporters. Tosi said the survivors included 45 women and three children. When rescuers stepped aboard, the bodies of migrants were "lying in water, fuel, human excrement" in the hold, Tosi said, adding that among the survivors, "women were crying for their husbands (and) their children who died in the crossing." Prior to Saturday's disaster, at least 2,100 migrants died at sea this year trying to make the crossing from the shores of Libya, where human traffickers are based, to Italy. Migration organizations say the Libya-to-Italy crossing is by far the deadliest. The exact toll of dead will never be known, as some boats are believed by authorities to have gone down at sea without rescuers being aware of them. The number of migrants trying to reach Europe by sea is on track to hit a record this year, according to the Geneva-based International Organization for Migration. Greece has reported 134,988 arrivals from Turkey this year, the group said, while Italy recorded more than 100,000 migrants rescued at sea by mid-August. Along with other migrants landing in Spain and Malta, that makes over 243,000 people crossing so far this year - compared to 219,000 for all of 2014. Also on HuffPost: -- This feed and its contents are the property of The Huffington Post, and use is subject to our terms. It may be used for personal consumption, but may not be distributed on a website.