Complex sentence: Cisneros was outraged by the appearance of Castelli and Rodríguez, who came armed and without an appointment, but they reacted harshly and demanded an immediate reply to the request for an open cabildo.
Split into simpler sentences: Cisneros was outraged by the appearance of Castelli and Rodríguez, who came armed and without an appointment. They reacted harshly and demanded an immediate reply to the request for an open cabildo.