Yavapai County has released video from an incident when a dog was left tied up behind a semi.
Spokesman Dwight D'Evelyn said a county volunteer was pulling out of a gas station after stopping to get a drink when he noticed a semi-tractor trailer pulling out with a dog still tied up.
The volunteer turned on his lights and siren to get the semi to pull over, which it did. Watch video of what happened in the player above.
The driver of the semi was grateful, retrieved his pet and thanked the volunteer for alerting him.
The sheriff's office says the driver was distracted and headed toward the interstate, forgetting to unleash his dog.
No charges are being sought in the incident.
The volunteer is part of the sheriff's office's Volunteer in Protection program, which sends people into the field to assist deputies with aspects of law enforcement, including transporting prisoners, assisting motorists and traffic control.
A review by sheriff's office commanders found the volunteer's use of lights and sirens to save the dog from injury or death was warranted.