Miss Riverton, who was arrested last week for allegedly throwing homemade bombs, has been charged along with three others with multiple felonies.
Kendra McKenzie Gill, 18, was charged Friday with four second-degree felony counts of possession of an explosive device. She is to appear in 3rd District Court in West Jordan on Aug. 26.
Her 18-year-old co-defendants Bryce Christopher Stone, Shanna Smith and John Reagh were given the same charges. All four remain free pending court appearances.
According to a probable cause statement filed in 3rd District Court, the four friends drove around neighborhoods in Riverton on the evening of Aug. 2 and threw bombs they made by mixing aluminum foil and toilet bowl cleaner into plastic bottles. Their intended targets were other friends of theirs and the bombs were meant as a prank.
All four teenagers were interviewed by police, and each allegedly confessed to having thrown a bomb at least once. No one was injured.
Gill topped a slate of nine beauty contestants earlier this summer in the Salt Lake City suburb. She showed off years of piano training with a Scott Joplin number and took home a $2,000 scholarship.
The Associated Press contributed to this report.