INSTITUTE, W. Va. (WSAZ) -- State police in Huntington are mourning the loss of one of their K-9s killed in the line of duty. The dog was fatally shot during a 10-hour standoff, but saved the life of a trooper.

Once a K-9 is fully trained and ready for duty, they spend every second with their handler, even go home with them, to help develop that very important relationship and bond. So when one is hurt or killed, it's like losing a partner.

"A dog's number one tool is its sense of smell," says Sergeant Ron Arthur, director of the West Virginia State Police K-9 Unit. "Its number one usefulness is as a locator."

That is why K-9s are used in so many different ways to assist police whether it be for a narcotic bust or tracking a missing person.

Sergeant Ron Arthur says from day one of training he develops a very special bond with the dogs.

"Every dog I've worked with I feel like is my partner," says Sgt. Arthur.

When a K-9 is lost in the line of duty, like what happened Saturday during a 10-hour standoff in Lincoln County, to troopers, it's like losing one of their own.

"If you work with someone for a minimum of eight hours a day, usually more, you build a little bit of a bond," says Sgt. Arthur.

But as much as a dog can feel like your companion and buddy, Arthur says you have to remember their purpose.

"They're a great tool, and I don't mean to sound insensitive, but they are a tool," says Sgt. Arthur. "Realizing that and training with them as a tool makes everyone safer, officers and the public."

Dogs may be deemed man's best friend, but when it comes to K-9s on the clock, many times they turn from best friend to savior.

A trooper was injured during that standoff Saturday. The suspect, Jesse Stacy, who barricaded himself inside his home and fired at officers, was killed when officers returned fire.