Human traffickers forced at knifepoint some 300 Africans to jump into the sea off Yemen early Friday, causing at least 32 migrants to drown, according to a Yemeni security official. The Africans - mostly Ethiopians and Somalis - were packed into two rickety boats that had crossed the Gulf of Aden from Somalia when their crews forced them overboard as they approached the Yemeni coast, the official said, speaking on condition of anonymity because he was not authorized to talk to the media. The official reported the survivors as saying that those who stood up to the crew got stabbed and beaten and were then thrown overboard. The incident is the latest in a series of cases of abuse of would-be migrants trying to flee the Horn of Africa for Yemen. The government said Thursday that about 5,000 illegal migrants from Ethiopia and Somalia had arrived in Yemen since the beginning of the year, and that 395 passengers on such boats had perished. Many of the casualties were slain by traffickers, or they drowned after their boats sank or they were forced overboard, a government official said.