Bhishma Parva 120.2

Horsemen then fought not with horsemen and elephant-riders fought not with other elephant-riders. But like men seized with fury, O Bharata, they indiscriminately slaughtered men one another, O monarch, in that battle. Fierce and great was the carnage that then spread itself among the ranks of the two armies, as and elephants, by hundreds, were scattered slain in all directions.