Contain the situation from getting worse, going mobile and contain your emotions and fears.
Control the scene from getting larger, control your fears, and stay focused. Take control of the radio to get cover, assistance, and give responding units a size-up. You control the response and probably the demeanor of the situation for the most part.
Communicate to all involved, use your calming techniques, I call it tactical talking. Keep communication lines open, you may have to negotiate rather than engage. What is very important here is to communicate to yourself. Positive self-talk is important to keep your heartbeat and breathing under control, your emotions in check, and your energy focused. I keep hearing about surviving; it is all about winning to me.
So what if you have to disengage, call for some backups, and engage again? It may be far healthier and require fewer trips to the trauma center. Cops respect smart cops who know how to win without the drama and unnecessary risks.
Sure, cops like a challenge and do not like wimps. However, you must learn that there are real consequences in the street. Locker room banter and after hours socials bragging sounds cool, but the reality statement is going home at night in one piece - minus scars, stitches, and broken bones. I want you to win with your head and keep names off the wall. Now, go look for a cup of tea.