The three significant units were the Imperial Bodyguard, the Air Force and the Corps of Engineers; of the three, the most recalcitrant were the Engineers. So on 7 October soldiers loyal to the Derg stormed the engineers' camp, killing five, wounding several and detaining the rest. As Bahru Zewde observation he said that, "With that, the illusion that the revolution would remain bloodless was exploded."[7]