On 14 November 1519, Cortes seized the emperor Moctezuma II and ordered the destruction of all the religious relics of the Aztecs. He ordered a Catholic cross placed on the Templo Mayor. While Cortes left for Veracruz to confront Spaniards looking to arrest him, Pedro de Alvarado learned of a plan to attack the Spaniards, and staged a pre-emptive attack on the Aztecs in the Sacred Precinct while they celebrated a religious festival. Unarmed and trapped within the walls of the Sacred Precinct, an estimated 8,000–10,000 Aztec nobles were killed. When word of the massacre spread throughout the city, the people turned on the Spaniards, killing seven, wounding many, and driving the rest back to their quarters. The Spaniards were trapped between two Aztec forces and 68 were captured alive. Ten of these Spanish captives were immediately sacrificed at the Temple and their severed heads were thrown back to the Spaniards. The others were sacrificed at the Great Temple that night, which could be seen from the Spanish camps. The sacrificed Spaniards were flayed and their faces – with beards attached – were tanned and sent to allied towns, both to solicit assistance and to warn against betraying the alliance.