Separate the conflicting parties. Make sure they take some time to cool off if necessary. Speak with each individually making sure to give unbiased attention to their side of the issue. Speak with any supervisors or other emoloyees who may have insight into the conflict at hand (outside parties will tend to have a more unbiased view of the matter, as long as they're not close friends with one party and not with the other, make sure you're aware of any such allegiances when choosing who to question). After collecting as much information as possible be sure to write up a detailed summary of the situation, being sure to include any and all relevant information, even if it seems insignificant. After the cooling off period for the conflicting parties bring them together to discuss the situation, being sure to set clear ground rules for achieving civil discourse (no interrupting, belittling etc.) have them brainstorm ideas of how the situation could have been better handled as well as ideas of how to keep any future conflicts from getting "out of control" be sure to keep a record of this meeting which you'll want to refer to in creating a "conflict resolution agreement" outlining all the previous mentioned relevant information but focusing on the most constructive of input given by the conflicting employees. Have them sign this document, give them a copy and let them know the other copy will go into their employee file. Whatever disciplinary steps may need to be taken are obviously up to your discretion and the department policy.