reason for aggression

Question
Yikes! Tonight our bunny bit my daughter's arm (did not break the skin, thank goodness) as she approached her! (She was running loose in the family room). I could understand it if she were chasing after her, but she simply walked up to her to pet her! What could be happening here? I'd hate to think we can't keep her, but I'm very wary of handling her now! She's never shown this sort of aggression before! Is there a simple and obvious answer?
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Followup To

Question -
Hi,
Our normally, very docile bunny became a raging rabbit yesterday! As soon as our friends entered the room, she was running laps and lunging at everyone. It's probably important to mention that they had with them, a 1 month old baby bunny wrapped in a towel. Their household also has an almost adolescent bunny. Our bunny, however, is the only pet in our household. Needless to say, she ended up scratching one friend's arm, and biting (not breaking the skin) my daughter's 6-year-old friend. She ran and lunged at me and my daughter, who, by the way, normally cares for her, and often carries her around like a baby. She is extremely tolerant of my 7-year-old's petting and wrapping her up and has never showed any aggression before. We aquired her last December, the vet estimated that she was approx. 6 months old at the time, and we had her spayed in March. We are leaving for vacation soon and depended on these friends to help us care for our bunny (in our home) but now they are terrified of her! My question is this: is the "obvious" answer to her aggression, the baby bunny? the scent of their other bunny? the fact that they are "strangers"? and could she attack again, simply smelling the scent of their bunnies on their clothing? Obviously, they wouldn't bring any bunnies with them again, to care for our rabbit. She did seem calmed down in the evening after they left, even back to "normal" but I'm wary of my daughter handling her now as well.

Answer -
It sounds as if your rabbit decided that the other bunny was infringing on her territory and was defending it.  This isn't uncommon behavior in rabbits.  

You might try having them come over without the rabbit, and make sure they have washed their hands and possibly even changed clothes if they have touched the baby bunny to see if that will help.

You can also find other information here that may help you - http://homepage.mac.com/mattocks/morfz/rabcare.html#aggbun.

Good luck.

Kim

Answer
She may still be mad at you for bringing the other bunny into the house.  I might suggest keeping her caged for the time being, both for your own safety and hers.

Once she has stopped this, then she can be let out again.

If she gets territorial in the cage too, when you open the door let her eat out of the cup of pellets first, so while her mouth is full you can put the rest in her dish.  That way she can't bite anyone.

Once you are back from vacation, she should have forgotten about this and you can go back to having your nice bunny.

Kim