What does a 1084 code on police scanner mean?

a code 1084 means 2 things: 10 designates that the unit requesting the dispatch is a police officer, and 84 means all units available nearby (within a set radius) respond to deadly (or will be soon) situation. usually not used unless a suspect is either armed and resisting custody or fleeing the scene and personnel is needed.

If you listen to the scanners sometimes you will also hear the call for 1584 whereas the 15 means EMT instead of the 10 given to police personnel.

I hope this answers your question. ;D

Sincerely EMT - P