The "hooded" people pictured above and below are members of one of many "brotherhood" organizations (these include women as well) that represent different churches in the area. These brotherhood organizations are associations of Catholic laypersons who perform public acts of religious observance. During Holy Week, the observances are related to the Passion and death of Jesus Christ and to performing public penance. The hoods signify mourning--their faces are covered as a sign of shame for sins committed throughout the year.
Watching a Semana Santa procession is an experience you won't likely forget...though more intense and unexpected the first time, the second year was more meaningful because the shock and awe had worn off. Looking forward to seeing what next year holds!