5yr old girl with Anger issues

My Daughter has been displaying anger management issues the last year or so. She tackled and choked a little girl at preschool. When asked why, she stated that she(my daughter) wanted to be the line leader, but the other girl was. And today in Kindergarden, She bit a child so hard that she drew blood. She said it was because he wasn't watching where he was going and ran into her. I have never displayed violence, and neither has her father. She's never allowed to watch violent t.v. shows or movies, and She is disciplined in the regular matter. I have caught her attacking the animals when she gets angry. I am afraid she might do something horrible if this anger issue isn't corrected right away. I do not know how to fix this, I am so upset over these incidents and I do not know how to cope. Please Help.

[specialmom]

Obviously, the school will begin to address this with her as they can't have a child doing these things to the other kids.  I hate that feeling of dread you get when the teacher calls . . .I've been there.  

Your daughter clearly has issues managing her anger.  She is young and has a "fight or flight" response to her anger and frustration.  She is choosing fight.  There may be an underlying cause of this whole transition to kindergarten is overwhelming to her (as it is to many kids) and she isn't coping well.  Kids also get very tired when starting "real" school.  Behavior goes down hill when tired as all parents know.  She needs to be given alternatives to her aggressive behavior.  Impulse control is slower to develop in some kids.  The key is to get the pause before she acts so that she can think of another way of handling her feelings.  This is when as an adult you are so mad at someone that you want to scream and get in their face.  You stop yourself (hopefully) after an instant of wanting to do it.  I would work on giving her words for the feelings.  There are plenty of books at the library for this.  My son described his anger as a tornado for about a year after reading a book.  It sounds silly----  but he would stop and say "I feel like a tornado!!!"  (or a storm cloud which was also bad, lol)----  and it was that pause we needed to step into alternative choices of how to react.  So give her words for the emotions.  
Then give her the alternative choices.  ----  tell the teacher with words what she is upset about.  (even if it is silly like she wants to be the line leader---- better to have her complain to her teacher than tackle her friend).  "Use your words" is a theme at our house.  She can take deep breaths, count to ten, open and shut her fists tightly, go to a quiet, calm down spot in the room set up ahead of time.  
Like I said, the school will probably be addressing this soon.  They will most likely recommend an evaluation.  Go ahead with it as more information concerning our children is always valuable.  She doesn't sound from this to have any delays (I have a 5 year old with a developmental delay and a 4 year old that does not) so I wouldn't really worry about that.  But the violent behavior needs to stop.  If there is a mental health reason, you'd want to know.  Keep younger kids and animals in your sight if possible so she doesn't hurt them.  Lots of luck to you.