My middle girl is very very strong willed and I am still learning. What I have learned best is to stay calm. The more you yell at them the more frustrated and angry they are going to get to. No matter how much they are scream try to keep calm put them in their room until they calm down even if it takes an hour.
Go in there and get to their level and explain to them why their behavior or how what they did was wrong. In the end take away things, ground them to their rooms, etc just like you would with any other chilld