Mbh 7.109.2c

And amongst all the troops of the Pandavas and the Panchalas, men quietly beheld brave Drona slaying the foremost of warriors in succession. Having slain a hundred warriors amongst the Kekayas and routing them on all sides, Drona stood, O monarch, like the Destroyer himself with wide-open mouth. The mighty-armed Drona vanquished the Panchalas, the Srinjayas, the Matsyas and the Kekayas, O monarch, by hundreds and thousands. Pierced by the arrows of Drona, the clamour made by them resembled that made in the woods by the denizens of the forest when encompassed by a conflagration. The gods, Gandharvas, and the Pitris, said, “Behold, the Panchalas, and the Pandavas, with all their troops, are flying away.” Indeed, when Drona was thus engaged in slaughtering the Somakas in battle, none ventured to advance against him and none succeeded in piercing him. And while that dreadful encounter, so destructive of great heroes, continued, Pritha’s son (Yudhishthira) suddenly heard the blare of Panchajanya. Blown by Vasudeva, that best of conchs gave loud blasts. Indeed, while the heroic protectors of the ruler of the Sindhus were fighting, and while the Dhartarashtras were roaring in front of Arjuna’s car, the twang of Gandiva could not be heard. The royal son of Pandu repeatedly swooned, and thought, “Without doubt, all is not well with Partha, since that prince of conchs (Panchajanya) is yielding such blasts and since the Kauravas also, filled with joy, are incessantly uttering such shouts.” Thinking in this way, with an anxious heart, Ajatasatru, the son of Kunti, said unto him of the Satwata race (viz., Satyaki) these words in a voice choked with tears. Though repeatedly stupefied, king Yudhishthira, however, did not lose sight of what was to be done next.