A fire that injured six firefighters in Vienna was intentionally set. That’s the word from Maries County Sheriff Chris Heitman, who tells KRMS News that propane was the source of the explosion that occurred last Friday. The firefighters continue to recover after having been treated for second and third-degree burns. The fire department says two of them have returned to at least partial duty. Sheriff Heitman says they do have a couple of suspects in the case and he anticipates making arrests within a matter of days.