What advice can I give to my aunts for their kids?

My my two aunts moved into a crappy neighborhood here in Southern California about an hour away from LA. In the two weeks that they've been here, my 17 and 15 year old male cousins have had their lives threatened by the black kids at their high school. One instance involved the older cousin being held up to a wall with a switchblade being stuck near his neck. Now they're terrified to go to school. Before you ask or accuse us of such, neither I nor my cousins hold any prejudice against black people. In this case, it seems to be the other way around actually, but one can never be too sure. Anyway, both my aunts went and talked to the principal of the school on behalf of their respective kids, but he refused to do anything about. He claims that because no one on his staff saw anything they can't prove anything actually happened. I think it's absolutely ridiculous. I was wondering if it's possible for them to start being home-schooled or find an independent studies program so they could just do their work at home and not continue to be harassed/threatened by these kids.