I am not saying that this is happening to your daughter, however i have a friend with a son that was showing the same behavior towards his sister. He would throw violent temper tantrums, hit and kick anyone that was around. He was actually put in a mental institution at age 4. It actually turnes out after being tested by a Psychologist he has bi-polor disorder. The reason i am telling you this is: because time outs don't work and spanking doesn't work, you may want to at least consult with your dr. Again I am not saying that this could be going on with your daughter, but on the other hand it is better to be safe than sorry.
Any aggressive behavior from a child should be met with immediate time out (see SOS Help for Parents). In addition, though, I suggest you arrange an evaluation with a pediatric mental health professional because the behavior may indicate the presence of some emotional disorder and this needs to be considered.