Lord of the Flies Classroom

The past month has been crazy in my classroom (third and fourth grade). I totally understand that this is my thought about it and not a circumstance. I have several students with behavior such as refusing to do work, talking when they should not be talking (and getting many to follow along at loud levels), having meltdowns that include throwing things like books and chairs, and not following our classroom rules. This escalates during reading workshop and math. I am feeling like I am completely losing control of my classroom. Yes, I know that is just a thought which I am proving each day. My models:
C-Students are not following class rules
T-I am losing control of my classroom
F-anxious, overwhelm
A-Yell, stop teaching and wait for compliance
R-Students briefly comply then go back to off task, some completely disregard my direction

C-Students are not following class rules
T-How do I reinforce the class rules?
A-do nothing
R-Students are not following class rules

C-Students are not following class rules
T-I need to go back to square 1 and re-teach class rules like the beginning of the year.
A-Reteach all rules and management system for infractions