Titus Livius (Livy), The History of Rome, Book 30
Frank Gardener Moore, Professor Emeritus in Columbia University, Ed.

6. When the light of the fire had been seen, first by sentries of the Carthaginians and then by others whom the uproar in the night aroused, they likewise made the same mistake in believing the fire to be spontaneous. [2] And outcries raised in the midst of slaughter and wounds made men unable to grasp the real situation, being half-inclined to think it due to a disturbance in the night. [3] Accordingly, having no suspicion of any attack, they outdid one another in dashing out of all the gates unarmed, each taking the nearest way, carrying only what would be of use to extinguish the fire, and suddenly encountered the Roman column. [4] When they had all been slain, not only because of an enemy's hatred, but also that no man might escape to tell the tale, Scipio at once burst into the gates, naturally unguarded in such a commotion. [5] And then as firebrands were thrown upon the nearest roofs, the flames pouring out at first seemed to blaze at a number of scattered points; and then creeping along without a break they promptly consumed [p. 385]everything in one conflagration. [6] Men and beasts¹ of burden that had suffered burns blocked streets leading to the gates, at first by their panic-stricken flight and then by their fallen bodies. [7] Those whom the fire had not overtaken were destroyed by the sword, and two camps were wiped out in a single disaster. Both of the generals, however, made their escape, and out of so many thousand armed men two thousand infantry and five hundred² horsemen escaped half-armed, many of the men wounded and scorched by the flames. [8] Slain or burned to death were some forty thousand men, more than five thousand captured, many Carthaginian nobles, eleven senators. [9] Of military standards a hundred and seventy-four were taken, of Numidian horses over two thousand seven hundred. Six elephants were captured, eight destroyed by sword or by fire. A great number of arms were captured, and all of these the general-in-command dedicated to Vulcan and burned.³