"They use it as a big waterslide," Sheriff Darin Halverson said, per Star Tribune. "Kids like to do that... They use tubes or whatever. Lots of times they go over on their own."
He said that if Raina hadn't saved her family members — the youngest of which was just six — "We probably would have had multiple fatalities."
"The water is just churning under the dam... She did her part and saved who she could."
Raina's heartbroken uncle agreed: "We could have been burying five of them out of the eight."
He told the publication the group had been swimming at the spot at least three other times this summer, but "8 inches of rain turned the river into a rapids.... They didn't realize where the undertow was, and them little kids went under."
A GoFundMe to raise money for the family of the heroic teen has raised $6,000 so far.