Contain the situation from getting worse or 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 and find cover. Ask for 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 and use your calming techniques. I call it tactical talking. Keep communication lines open; you may have to negotiate rather than engage. What's very important here is that you communicate with yourself. Positive self-talk is important to keep your heartbeat and breathing under control, your emotions in check and energy focused. I keep hearing about surviving; it's all about winning to me.
What if you have to disengage, call for back-up and engage again? It may be far healthier and less trips to the trauma center. Cops respect smart cops who know how to win without drama or unnecessary risks.
Sure, cops embrace a challenge and don't like wimps. However, you must learn that there are real consequences in the street. Locker-room banter and after-hours social bragging sounds cool, but the reality is you need to go home in one piece without scars, stitches or broken bones.