Mbh 6.59.2a

Sanjaya said, “After the forenoon of that day, O Bharata, had passed away, and the sun in his westward course had passed a portion of his path, and after the high-souled Pandavas had won the victory, thy sire Devavrata, conversant with the distinction of all codes of morality, rushed carried by the fleetest steeds, towards the army of the Pandavas, protected by a large force and by all thy sons. Then, O Bharata, in consequence of thy sinful policy, commenced a dreadful battle, making the hair stand on end, between ourselves and the Pandavas. And the twang of bows, the flapping of bowstrings against the leathern fences (casing the hands of the bowman), mingling together, made a loud uproar resembling that of splitting hills. Stay--Here I stand,--Know this one,--Turn back,--Stand,--I wait for thee--Strike,--these were the words heard everywhere. And the sound of falling coats of mail made of gold, of crowns and diadems, and of standards resembled the sound of falling stones on a stony ground. And heads, and arms decked with ornaments, falling by hundreds and thousands upon the ground moved in convulsions. And some brave combatants, with heads severed from their trunks, continued to stand weapons in grasp or armed with drawn bow. And a dreadful river of blood began to flow there, of impetuous current, miry with flesh and blood, and with the bodies of (dead) elephants for its (sub-aqueous) rocks. Flowing from the bodies of steeds, men, and elephants, and delightful to vultures and jackals, it ran towards the ocean represented by the next world. A battle such as that, O king, which (then) took place between thy sons, O Bharata, and the Pandavas, was never seen or heard before. And in consequence of the bodies of combatants slain in that conflict, cars could not make their way. And the field of battle in consequence of the bodies of slain elephants seemed to be strewn over with blue crests of hills.