LAKESIDE, Calif. — A 10-year-old California girl was fatally struck by a runaway vehicle while heroically pushing two children out of harm’s way, au...

LAKESIDE, Calif. -- A 10-year-old California girl was fatally struck by a runaway vehicle while heroically pushing two children out of harm's way, authorities told KSWB.

Neighbors told KGTV the children were playing in the yard on Monday when it started rolling. Kiera Larsen instinctively pushed two toddlers, ages 1 and 2, out of the path of the SUV.

The vehicle struck the 10-year-old and pushed her through a fence, according to KGTV. Paramedics took the girl to a local hospital where she later died.

Authorities did not say how the 1999 Mercedes-Benz began rolling in reverse down the dirt driveway.

“She is truly a hero. She will forever be my kids’ guardian angel,” said Alissa Jenkins, mother of one-year-old Adison and two-year-old Emma, the two girls Kiera saved. “She saved both my daughters' lives. These are my two kids that I have and both of them could’ve been gone in an instant and she stepped in and took over and did what she knows best to do -- and that’s to protect those around her.

Jenkins and her fiancé Jonathan Gusich say they will never be able to repay Kiera for her selfless act.

"She was a big sister to them. She was always looking out for them and apparently she gave her life for my kids,” Gusich said. “I don’t know how to repay them, repay her. She must have been the guardian angel yesterday and they’re here because of her.”

Police are inspecting the vehicle to find out why it happened, and to determine whether a malfunction caused the vehicle to roll.

“A child died heroically. I mean if you think about it, she sacrificed herself for another small child," CHP Officer Kevin Pearlstein said.