SANTA CATARINA PINULA, Guatemala, Oct 5 (Reuters) - Beneath the mud and rock that engulfed the small Guatemalan town of Santa Catarina Pinula last week, search crews have found entire families who died huddled together after they were buried alive. At least 132 people were killed in Thursday's disaster just outside Guatemala City, and emergency services chief Alejandro Maldonado said on Monday at least 300 people were still unaccounted for.