I think my dad might kill me and my family. What should I do?

My dad has mental problems and he’s been in and out of the mental hospital multiple times. He has a ton of outbursts and he has a lot of anger toward myself, my sister & my mom—he blames us for all of his problems in life and has a ton of anger and hatred towards us. Last night, he and my mom had a huge fight (way bigger than “normal”) and now my sister and I are scared that he’s going to hurt us or maybe even kill us. We tell our mom that we’re scared he might do something, but she’s in denial and says “he wouldn’t do that.” I know what he’s capable of, he nearly punched me in the face for no reason once when he was having a psychotic outburst and I was only 16 at the time. His family doesn’t live in the same state as us & they don’t want him at their house so sending him to live with them isn’t an option. If you have any suggestions about what I could do or say to my mom so that this doesn’t happen, please comment. I’m open to all suggestions. Thank you.