From Fray Bernardino de Sahagún, Florentine Codex, Book 12, Chapter 35 (Mexica)

Here it is told how once again the Mexicas took captives--according to the count of the Spaniards, there were fifty-three, as well as many Tlaxcalans and people of Tetzcoco, Chalco, and Xochimilco--and how they sacrificed them before their former gods.

At this point [after a long siege of Tenochtitán], the Mexica warriors threw themselves [into the open] and chased [the Spaniards]; they ambushed them from the passageways, and when the Spaniards saw it [they believed that the Mexicas] seemed drunk. [The Mexicas] then took captives. Many Tlaxcalans, and people of Acolhuacan, Chalco, Xochimilco, etc., were taken. A great many were captured and killed. They forced the Spaniards and all the others to go right into the water.

And the road became very slippery; one could no longer walk on it, but would slip and slide. And the captives were dragged along the trails.

[The chapter then mentions how the Mexicas and their allies captured the Spaniards' standard, but the Spaniards were too worried to care about it.]

Then they took the captives to Yacacolco, hurrying them along, keeping them together. Some went weeping, some went singing, some went shouting while clapping their hands against their mouths. When they got them to Yacacolco, they lined them up in rows, in files. One by one they proceeded to the small pyramid where they were slain. The Spaniards went first, going in the lead; the people of all the different [allied] cities just followed. And when the sacrifice was over, they chopped off the heads of the Spaniards. They strung the Spaniards heads on poles [on the skull rack]; they also strung up the heads of the horses, arranging them below, while the heads of the Spaniards were above. They placed them so they faced east toward the rising sun. But they did not string up the heads of all of those from the allied towns, nor did they string up the heads from those who had come from far away. There were fifty-three Spaniards they captured and four horses.

Nevertheless, [the Mexicas] kept watch everywhere, and there was fighting. [In spite of their success in capturing the Spaniards], they kept watch everywhere. The people of Xochimilco went about in boats surrounding us on all sides. On both sides captives were taken; on both sides there was killing.

And all the common people suffered from hunger; many died of hunger. They no longer drank good, pure water, but the water they drank was salty. Many people died of it, and because of it many got dysentery and died. Everything was eaten--lizards and swallows; and maize straw, and grass that grows on salt flats. And they ate colorin wood; they chewed on glue flowers, plaster, leather, and deerskin, which they roasted, baked, and toasted so that they could eat them, and they ate rough herbs and even mud [bricks].There had never been such suffering. It was terrifying how it is to be besieged, and great numbers died of hunger. And little by little they [the enemy] pressed us back against the wall; hemmed us in and contained us.