child with viloent behavior at home and school

my child is in grade one and she has had a first good 2 years of school and this year she is acting out badly to the point that the school called me and said the child cant come back until they get the right people in to help with my childs behavior problems and the child as started acting out at home telling us the parents shes gonna kill us and spits in our faces and constantly hits us.these problems have never happened before until the last 3 weeksof school i dont understand i feel my child is a stranger to me .i dont understand why the other 2 years were fine and this last while everything has been upside down.is this normal if not what could it be .help!!!!!!!!