The first Officer to arrive must secure the scene
Always keep in communication with dispatch and advise any units who are en route to the scene of what is happening.
Make sure you collect all evidence from the scene i.e. license plates etc. This is your responsibility as the first on the scene. If you are an active CID, you are to remain behind to conduct interviews with hostages and collect evidence.
Once the situation has been called “code 4” it is then your responsibility to make sure that all units are aware of the list of charges for anyone that has been arrested.
If you must leave to go off duty, make sure you pass on all relevant information to any other LEOs in the area.