So take her to the emergency department. Don't make up any story, just tell them what happened. They will contact the proper authorities.
If you don't want to do that then call the police,
a trusted relative, anyone who can get you out of the situation. Its scary to do I know, especially if your talking about a parent, but do it anyway.
Violent people only tend to become more violent.
They don't just suddenly stop. Get out of the situation before it gets worse.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.