A 12-year-old boy drowned after he tried to ride the middle chute of a dam like a water slide, and his older brother died trying to save him.

Brandon Dornbusch, 12, became trapped Monday in the swirling water below the small spillway, a narrow channel that carries water from the Chippewa River (search) beneath a road bridge, authorities said.

"It looks like something you'd see in a water park, but it isn't. Not anywhere near that. It's deadly," said deputy Tim Christensen of Chippewa County in southwestern Minnesota.

Brandon's older brother, Justin, 14, tried to help, first using a fishing pole but then following his brother down the same, smooth-looking chute. He, too, was caught in the powerful water.

Their 11-year-old stepsister, Chelsea, bicycled nearly a mile to town to summon help. Rescuers later found the boys' bodies downstream.

Mona Dornbusch, the boys' stepmother, said they had gone to the dam to fish and that she had warned them to stay on shore. She said the boys had been each other's protectors.

"They weren't done with their lives yet," she said, fighting back tears.

The family had moved to the area from Texas earlier this year to make a new start, Mona Dornbusch said. Now, she said, her husband wishes he had never made the move.

Christensen said that to his knowledge, the drownings are the first at the spillway in the 23 years he has worked for the sheriff's office. Heavy spring rain had nearly quadrupled the water flow over the spillway.

There are no signs posted by the bridge warning swimmers to stay clear. However, the U.S. Army Corps of Engineers (search), which operates the dam, posted life-preservers on each bank of the river to use in case of emergency.

"To a kid, it looks like fun," Christensen said. "But kids, and I'm sure some adults, they don't understand the power of hydraulics. We have to teach kids to stay away from these."