Officials at The Elephant Sanctuary in Hohenwald, Tenn., said Friday that Bella, a rescue dog whose longtime companion had been Tarra the Asian elephant, was killed earlier this week.The best friends were the stars of the sanctuary and even had a book written about them.

Here's a CBS video about their incredible friendship:

Here's a portion of today's announcement from the sanctuary:

Tarra's little dog Bella has died. We found her body on Wednesday and have been dealing with the aftermath ever since, trying to work out what happened while we look after Tarra and each other.

We noticed Bella was not with Tarra at breakfast on Tuesday and later that morning she still had not appeared. Tarra and Bella have always spent short periods apart as one goes off exploring briefly on their own, but this longer absence worried us deeply and a search of the property was started which continued into the next day. The search ended tragically when Bella's body was found close to the Asia barn that had long been home to Tarra, her five sisters and Bella. During the time of the search our usually social Tarra chose to remain alone, watched over by concerned caregivers.

Dr. Scott, our vet of sixteen years, examined Bella for the last time and, with advice from the experts from the Tennessee Wildlife Resources Agency, determined the probable cause of death was an attack by animals, most likely coyotes.

Meantime, sanctuary co-founder Carol Buckley, who is now involved in a dispute with the sanctuary board over her dismissal last year, says that Tarra the elephant is no doubt suffering emotionally from the loss of her friend. She writes in an email:

Without question Tarra is suffering great emotional pain from witnessing the death of her best friend. Knowing the depth of emotion that elephants experience, I can hardly imagine how Tarra is feeling.

Bella was a special girl, an independent and sweet soul, and a loyal and sincere friend to Tarra. Their relationship spanned a decade and demonstrated their boundless capacity for love. They taught the world that things are not always as they seem when an 8,000-pound elephant and a 40-pound dog choose one another over anyone else.

Buckley wrote that she has petitioned the sanctuary to allow her to visit Tarra to help comfort her.