Preliminary autopsy results show two brothers found in the Snake River near Firth had been shot, Bingham County authorities said.

Sheriff LeRoy Nelson said Monday the parents of Aaron Annett, 16, and his brother, Kevin, 13, reported the boys missing Saturday afternoon, prompting a search.Later, children playing near the Snake River found the body of Aaron in the water. The search for the second brother was intensified, and the body of the second youth was finally found Sunday morning in the same general area of the river.

Authorities said it was still not clear whether the boys died of the gunshot wounds or drowning.

Bingham County Prosecuting Attorney Thomas Moss has declined to say whether there were suspects in the case. He said that investigators have "a significant amount" of evidence, but no arrest warrants have been issued.