Most of the tensions between the two professions don't bubble up into the news. When they do it isn't the type of press coverage that you want to have on your department and your personnel. See this NPR story Police Officer Arrests Firefighter At Accident Scene In California
I'm sure there are better ways to demonstrate cooperation. Neither the fire service or law enforcement wins with the above image plastered on the Internet.
Lastly, another dynamic I've watched over the years with the onset of Homeland Security Grants is how these two professions compete for grant funding. Each is looking at who is getting what and thinking they got short changed in the grant process. I guess it is just human nature that bubbles over into our daily work lives as emergency managers. I had an old boss who used to say, "Don't be looking at what someone else has on their plate, eat the peas on your plate."
Steve Myers shared the link to the story.