Josephus, Antiquities 18.60-62
But Pilate undertook to bring a current of water to Jerusalem, and did it with the sacred money, and derived the origin of the stream from the distance of two hundred furlongs. However, the Jews were not pleased with what had been done about this water; and many ten thousands of the people got together, and made a clamor against him, and insisted that he should leave off that design. Some of them also used reproaches, and abused the man, as crowds of such people usually do. So he habited a great number of his soldiers in their habit, who carried daggers under their garments, and sent them to a place where they might surround them. So he bid the Jews himself go away; but they boldly casting reproaches upon him, he gave the soldiers that signal which had been beforehand agreed on; who laid upon them much greater blows than Pilate had commanded them, and equally punished those that were tumultuous, and those that were not; nor did they spare them in the least: and since the people were unarmed, and were caught by men prepared for what they were about, there were a great number of them slain by this means, and others of them ran away wounded. And thus an end was put to this sedition.