On the blast door map there are several mentions of "cerebus system". According to the dictionary:Cerberus (sūr'burus), in Greek mythology, many-headed dog with a mane and a tail of snakes; offspring of Typhon and Echidna. He guarded the entrance of Hades. One of the 12 labors of Hercules was to capture him.
Notice that Cerberus is a "guard" - hmmm just like what the smoke monster was described as - a "security system".
Could the black smoke "monster" be the Cerberus System and has malfunctioned?
Time will tell and we can guess in the mean time