Avoid becoming a victim of property crime with residential and commercial security systems from our company in Sonora, California. Family-owned-and-operated MOUNTAIN ALARM is Tuolumne County's most experienced and longest established security system and fire alarm company. We are the only alarm company in the county that has a brick and mortar location. Depend on us to be courteous, respectful, and sensitive to your security needs. We are always here for our customers.