7:52 a.m.
Deafening detonations from the interior preceded this appearance , and a lofty white pennant was seen to rise from the summit of the volcano . `` With wild fury the black cloud rolled down the mountain slope , pressing closely the contours of the valley along which had previously swept the mud-flow that overwhelmed the factory three days before , and spreading fan-like to the sea . `` In two minutes , or less , it had reached the doomed city , a flash of blinding intensity parted its coils , and St. Pierre was ablaze . The clock of the Military Hospital halted at 7:52 a.m. -- a historic time-mark among the ruins , the recorder of one of the greatest catastrophic events that are written in the history of the world . '' Just before the cloud struck , its violet-grey center showed , and the forepart of this was luminous . It struck the town with the fury of a tornado of flame . Whirls of fire writhed spirally about it .