Sounds like a horrible situation!
The best thing would be to ran away and hide, but at the same time they are the perpetrators. So why should you hide? Try to fight back, make them pay! Maybe enlist help from your siblings, if they feel the same?
I know it might be naive, but did you try talking to the police? Maybe heve them on tape and get a restraining order? Or try provoking them into doing something illegal and get them go to jail or deported! They came to this country, so they should follow the traditions of the civilized world! If they don't - they should pay! THe only way to fight bullies is to stand up to them!
Cheers