First, take a breath!  Find your way to personal calmness and take a quick observation as to what’s causing and fanning the sibling warfare.  Do they need to be separated?  Is there an underlying unresolved issue? Is a ceasefire in order?  Bring them to the negotiation table and give them each 2 minutes to speak and then make them come up with two ways to improve their relationship. Set some ground rules, work out differences, and discuss expectations for household harmony and how everyone is going to work together to help them get there.

Siblings will disagree and fight, but out of control fighting and yelling is jarring for everyone. So address it as a family, state repercussions, and carry through with sending them each to their rooms or loss of privileges, if fighting continues.