Police on scene say a white sedan with three juveniles inside was traveling southbound on Farmway when they entered the intersection on Old Highway 30, where it was struck by a manure truck.
"We are still investigating the crash but it looks like the car failed to stop at the stop sign or failed to yield from the stop sign pulling out on to the roadway and was struck in the driver side doorway by the manure truck," said Sgt. Jason Kagle of the Idaho State Police.
On Friday, the Canyon County Coroner's Office identified the deceased as 17-year-old Ashton Braden, and Sophie Moore, 6. Ashton would have turned 18 years old today (Friday).
The Associated Press reported the girls as sisters.
The other passenger, 11-year-old Zoey Moore, was flown to a Boise hospital with unknown injuries. The parents of the deceased have been notified.
The driver of the manure truck wasn't injured.