It appears that there has been a fire at a military base, which spread to a munitions depot, which turns out to be the main storage area for intermediate range ballistic missiles. Preliminary reports have the fire out of control and doing extensive damage.
The good news is that it's Iran's base at which they store their longest range missile, the Shahab-3 with a range of some 2500 miles. This is roughly equivalent of the old Pershing 2 system which we destroyed at the behest of the Russkies.
Bummer, dudes, but you really shouldn't allow smoking near the fuel dumps.