Residents of a small town in northern Utah struggled to comprehend Wednesday why two teenage boys plotted to rob and kill a 14-year-old girl before shooting her in the head and leaving her critically wounded in a ditch, according to prosecutors.

The 16-year-old suspects do not have any serious criminal history, and both had no known problems at Smithfield's only high school, court and school officials say. Police have not provided a motive for hurting Deserae Turner, who was in a medically induced coma, but one of the boys said they were driven by greed.

They told police they lured Turner to the ditch last week by promising to sell her a knife. Instead, they shot her and then took her cellphone, iPod and $55, prosecutors said in charging documents.

"What's hard for the community to process is why something like this would happen," said Tim Smith, spokesman for the Cache County School District, where all the teens went to school. "These types of events aren't typical for our valley."

Smithfield, with a population of nearly 11,000, is one of several small bedroom communities around Logan, the largest city in the northern part of the heavily Mormon state. Deserae attends the area's only middle school.

The teenage suspects have been charged with attempted aggravated murder, robbery and other counts.

Lawyer Shannon Demler, who represents one of the suspects, said he's still trying to understand what happened but that the allegations caught the boy's parents off-guard and has been very hard on them.

"This case has torn apart three families," Demler said. "And the community is shaken up that something like this could happen here."

A judge ordered the suspects to stay in juvenile detention after a brief court appearance Wednesday with their parents, the Herald Journal of Logan reported ( http://bit.ly/2lvZ073 ).

The Associated Press is not naming the boys because they are juveniles.

Demler said he will argue to keep his client in juvenile court, after Cache County Attorney James Swink said he wants to try the teens as adults.

Deserae was reported missing Thursday evening when she didn't return home from school. She was found early Friday in a dry canal about 90 miles north of Salt Lake City with a gunshot to the back of her head.

"She was a typical 14-year-old," Smith said of Deserae, adding that her family has asked for background about the ninth-grader to be kept private. "A good student. Great family. Very supportive family."

Smith said he was not aware of any past problems with the two boys at school.

Charging documents say the boys originally planned to stab Deserae with knives of their own. After they arrived, one boy decided instead to use a gun he had brought, prosecutors said Tuesday.

They took money, tossed her backpack in a trash bin and destroyed her cellphone and iPod, prosecutors said.

The teen who brought the gun gave the spent shell casing to the other boy when he asked to keep it "as a memento," the charges state. Officers later found it displayed on his bedroom windowsill.

The teen who took the casing home told police that he saw his friend shoot a girl he didn't know, though investigators say text messages between the boys indicate they planned the robbery and shooting together.

The teen accused of pulling the trigger gave police a written note for Deserae's family that said, "I am so so so sorry," authorities said.

Jill Parker, a county employee who is acting as a spokeswoman for Deserae's family, said they are doing the best they can. She declined to say why the family might believe their daughter was targeted.

Friends have set up a fundraising webpage that had brought in more than $30,000 as of Wednesday afternoon. The GoFundMe page says Turner is "fighting as hard as she can!" and adds that "every little bit will help their poor family with their ongoing family expenses as they go through this tough battle."

Information from ABC News was used in this report.