Idaho State Police said the truck crashed into the side of the school bus on its morning run to an elementary school Thursday, the Idaho Statesman in Boise reported.
Police said the dump truck driver, 33-year-old Charles Derby of Nampa, rushed to the bus to help calm the 12 riders and render aid.
"He knew there were kids hurt," Master Cpl. Tim Davidson said. "He saw the nitty-gritty, if you will, of the crash scene and the damage that had been done, up to and including the deceased boy."
State police spokeswoman Teresa Backer said a nurse who passed the bus moments before it was hit returned to the scene and performed CPR on 11-year-old Daniel Cook, the fatality.
The school bus driver, Debra Boatwright, 56, of Kuna, wasn't injured but was taken to a hospital because she was in emotional distress, police said.
The dump truck had numerous equipment violations but the school bus did not, the Statesman said.
Police couldn't say if those violations factored in the crash.
Davidson said charges "likely" would be filed, but investigators were still working to determine what had happened. State police in a statement said the investigation could take several weeks, after which charges, if any, would be filed.
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