I also work very closely with Technical Large Animal Emergency Rescue (TLAER), and live near Valley View Acres in Illinois, where 32 horses perished in a barn fire on Saturday, November 23, 2014. 
I have to disagree - barn fires are horrifically common. From Michigan to Illinois to Kansas (just overnight) to Georgia to California, over 200 horses have died in barn fires in the last 90 days (since October 2014).
Please come over to the TLAER Facebook page and just scroll through some of the recent stories: https://www.facebook.com/groups/tlaer/
Other owners are encouraged to take a proactive approach with their own properties, no matter how large or small. There are recommended best practices for animal housing in NFPA 150 (http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=150).
Most importantly, have your local fire inspector come out, inspect your barn, and make safety recommendations, the first of which should be to install a sprinkler system. There are many different sprinkler systems out there including what is known as a pre-action dry system that is commonly used in cold climates because it does not require the building to be heated since the sprinkler pipes are kept dry until they activate. Many barns and parking garages use them with great success and no freezing issues. Sprinkler systems start at $1.50 - $2/sf.
Next, have all electrical wiring reviewed by a licensed electrician familiar with the load used/required for barns. Add fire extinguishers and an alarm system. Store machinery, flammables and hay in a separate building. Create access to stalls not only on the inside of the barn but from the outside as well.
There are still instances when, despite all efforts, an emergency will happen. Ask your local fire department to get training on large animal rescue (running at large, trailer accidents, mud and ice rescue, and barn fires), which is a recognized technical skill under NFPA 1670. There are large animal rescue awareness classes taught by the University of Illinois Fire Service Institute (Illinois is the first state in the country to make this topic available at no charge to Illinois fire departments as part of the basic firefighter curriculum), and worldwide by Dr. Rebecca Gimenez, who will be speaking in McHenry County in June 2015.
Trail Riders of DuPage (www.trod.us/ert.htm) has been teaching hands-on horse handling to first responders in Illinois since 1994.
Education, awareness and proactive action can help prevent future fires.