A day of fun quickly turned tragic outside Texas Motor Speedway Sunday when a go-kart went out of control, killing the 14-year-old female driver.

The family of Kierstin Eaddy confirmed to NBC 5 that she was the teen driver killed in the crash. They said the Flower Mound resident was an honor student and a volunteer and that "they're trying to understand why God took such a special little girl today."

According to CareFlite, Eaddy was driving in a solo go-kart race when something went wrong.

Witnesses said she accelerated as she passed the finish line, a point when she should have been slowing down. The kart kept going until it hit a braided cable so hard that it took off the helmet she was wearing.

"Something happened, possibly her brakes went away or brakes went out," said John Ray, with North Texas Karters, Inc.

Eaddy was airlifted to an area hospital, but emergency crews could not save her.

Witnesses were stunned and horrified.

"It's terrible," said witness Nick Carmell. "I've raced karts myself. Never seen anything like this happen."

Eaddy often practiced at North Texas Kartway in Denton where other young drivers are now mourning her death.

"It is real tragic to hear when something like that happens. It's very rare, but when it does happen it's not very fun to hear," said go-kart racer Jacob Loomis.

Sunday's event was organized by the Sports Car Club of America, which often uses the parking lots at TMS to set up their tracks for both street cars and go-karts.

In a statement posted on the SCCA website, president and CEO Lisa Noble said:

"All of us at the SCCA are shocked and saddened to hear about Sunday's tragic accident involving Kierstin Eaddy. We are a Club of families, and are shaken by the loss of this young competitor. Personally, and on behalf of the SCCA, my heartfelt condolences go out to Kierstin's family, friends, and the participants at Sunday's event."

Texas Motor Speedway shut down all of its events after the wreck Sunday morning.

The Fort Worth Police Department is investigating the cause of the crash.