Want to marry my girl friend but her parents have house arrested her

i wants to marry my gf ..we both have attended the legal age...but the problem is that her parents are not agreeing for it..i have tried many times to convince them but they threatened to kill me...they have house arrested her snatched her phone not allowing to talk to anyone...but she is in touch whenever she finds some means...now please suggest me the best legal way that protects me and my family from legal hassles....she can come out of her home but then she cant go back... should we go directly to police station to seek help and file a complaint against her parents.vl thy help ?.