Still Speechless!!

Last Sunday I went with the girls to see my parents (Richard had a well-deserved "day off" role playing with his friends). My parents had invited a little 3-year old girl who spends a lot of time with them so the kids could all play together. At some point during the day I got to witness the following scene:

While the girls were all playing upstairs I was having coffee with my parents downstairs. Suddenly, the 3-year old called for my mother. We went upstairs to check what had happened. Obviously, Lily had gone in one of the rooms, closed the door behind herself and was now playing there. The girl demanded from us to order Lily to open the door. Of course we refused and told the girl to open the door herself; the girl shook her head saying that she couldn't open the door because Lily had told her not to do so. We told her that if she didn't open the door she would just have to play outside (where most of the toys were anyways). There, she just lost it. She was getting angry, yelling, screaming and threatening Lily to open the door; of course, Lily did not. The girl started flailing at the door like a little maniac, continuing screaming and cussing without ever once touching the door handle to simply open the door. I removed Violet from the situation and waited until the girl recaptured composure, which took her quite a while.

To be honest, I have seen my share of tantrums with our girls, but this scene just left me completely speechless! Even not quite 2-year old Violet would have gone and opened the door which had not been locked or barred. Right now I am considering contacting her daycare providers, who have before mentioned to her custodian that her behavior in the group was strange. Obviously she was more often than not simply sitting in her corner staring in front of herself and needs to be almost forced to participate in group activities. Am I exaggerating and is all this still normal behavior for a 3-year old?  

PS: This experience will probably be part of another post in the foreseeable future, but I'm still digesting on this experience and will need some time to put it in perspective. Any comment is highly appreciated!!