Sheriff's investigators say as deputies arrived, a Brinks armored truck driver was found laying on the ground with a gunshot wound to the upper body. Another man was also on the ground, with several gunshot wounds.
Investigators believe the security guard was walking out of a Golden One branch with a bag of money when a masked man armed with a gun tried to rob him.
Both men exchanged gunfire, Sheriff's spokesperson Tony Turnbull said, and both men were taken to the hospital in critical condition.
Good Samaritans at the scene helped the security guard using the very shirts off their backs, applying pressure to his wound before officers could arrive.