Stepmom gives heartbreaking update as last surviving daughter dies following mother's murder-suicide of all her kids

The sole survivor from the murder-suicide that saw three girls as young as two shot dead has tragically passed away.

After five days battling an unimaginable gunshot wound to the head, seven-year-old Olivia Blackmer died on Saturday afternoon (February 15). Her 32-year-old mother Tranyelle Harshman was the one who shot her and her sisters before she took her own life.

Tranyelle Harsman murdered all of her four children before killing herself (Tranyelle Harsman/Facebook)

Little Olivia is the last of the girls to die at the hands of her mom, with her nine-year-old sister and two-year-old stepsisters passing last Monday afternoon (February 10) at the scene of the crime in Wyoming.

Taking to the GoFundMe page setup to pay for Olivia's medical expenses, as well as for the kids' funeral arrangements, her stepmom Katelynn Blackmer shared the devastating news.

"Olivia is with her sisters now. She gained her angel wings yesterday at 3:44pm. She fought so so hard up til the last minute! Her body and her brain had been through too much, medication helped but we reached a point where medical options were exhausted and her body only continued to get worse," she wrote.

Olivia Blackmer has sadly died in hospital at the hands of her mom (Facebook/Katelynn Blackmer)

"She kept fighting through it all though until her heart stopped. We are grateful she hung on as long as she did so we could get some valuable time with our sweet baby girl the last five days. We want to thank each and every one of you for your prayers and support for our family.

"We are in a rough spot with the tragic passing of both daughters. We took time as a family to grieve and be in the moment before letting the world know but wanted to let you all know as we are thankful for all that you have done."

Adding: "Olivia and Brailey know how loved they were by all of us! This is going to be extremely hard, please keep our family in your prayers as we figure out how to grieve this horrific tragedy day to day."

Olivia has tragically passed away after five days of fighting (GoFundMe)

It comes as it was reported that Harshman dialled 911 herself at the time (February 10), to report that her four daughters had been shot, according to the local sheriff’s office.

She told the dispatcher where the girls were located in the house during the call, leading the officers to discover the bodies with gunshot wounds to their heads.

Olivia was the sole survivor at the time.

When Harshman was found, it was determined that she was alive, but she later died from her wounds.