Well, yesterday is probably not the best example as she well may have been goaded into that result. But some things to do. I would look into buying "Cool down and work through anger" or "When I feel angry". This is part of a series of books aimed at 4 to 7 year olds and meant to be read to them at night (several times) and then practiced. Kids do need to be taught how to deal with anger. You do not try and use these techniques while she is angry. But once she stops or later on in the day - you can refer back to them or pull the books back out.
You can find them here - http://www.amazon.com/Cool-Through-Anger-Learning-Along/dp/1575423464/ref=pd_sim_b_5
Hands are not for hitting is also a good book. It can be found here http://www.amazon.com/Hands-Hitting-Ages-Best-Behavior/dp/1575420775
Hopefully, the school does more then just call you. At this age its pretty hard to change a school behavior with things you do at home. The school needs to be taking an active roll too.
Finally, I always wonder when i hear an ODD case if the child does not also have ADHD. good link here - http://www.livescience.com/22362-adhd-symptoms-guide.html
The reason I mention ADHD is that 40% of kids with ADHD have ODD. It follows that a lot of kids with ODD then also have ADHD. Which also makes me wonder what kind of a doctor did the ODD diagnosis?
Anyway, here is a good link on ADHD an ODD - http://www.additudemag.com/slideshow/26/slide-1.html?utm_source=eletter&utm_medium=email&utm_campaign=December
I would have to know a lot more about what your daughter is doing to offer more specific advise. If it does seem like she also might have ADHD, you can also post to me over here -
http://www.medhelp.org/forums/ADD---ADHD/show/175